Subtracting 4x from Both Sides

Oct 13, 2025 by wbrum.org 102 views

A Man's Age and His Son: A Mathematical Puzzle

Mathematics is a fascinating subject that surrounds us in every aspect of life. It is a powerful tool that helps us solve problems, make predictions, and understand the world around us. In this article, we will delve into a classic mathematical puzzle that involves a man and his son. We will use algebraic equations to solve the problem and find the present ages of the man and his son.

A man's age is seven times that of his son. In 5 years, he will be four times as old as his son. What are the present ages of the man and his son?

Let's Break It Down

To solve this problem, we will use algebraic equations. Let's assume that the present age of the son is x. Since the man's age is seven times that of his son, the present age of the man is 7x.

Equation 1: Present Ages

The present age of the son is x, and the present age of the man is 7x.

Equation 2: Ages in 5 Years

In 5 years, the age of the son will be x + 5, and the age of the man will be 7x + 5. According to the problem, in 5 years, the man will be four times as old as his son. We can write this as an equation:

7x + 5 = 4(x + 5)

Simplifying the Equation

Now, let's simplify the equation by expanding the right-hand side:

7x + 5 = 4x + 20

Subtracting 4x from Both Sides

Subtracting 4x from both sides of the equation gives us:

3x + 5 = 20

Subtracting 5 from Both Sides

Subtracting 5 from both sides of the equation gives us:

3x = 15

Dividing Both Sides by 3

Dividing both sides of the equation by 3 gives us:

x = 5

Finding the Present Ages

Now that we have found the present age of the son (x = 5), we can find the present age of the man. Since the man's age is seven times that of his son, the present age of the man is 7x = 7(5) = 35.

In this article, we solved a classic mathematical puzzle involving a man and his son. We used algebraic equations to find the present ages of the man and his son. The present age of the son is 5, and the present age of the man is 35. This problem is a great example of how mathematics can be used to solve real-world problems and understand the world around us.

Additional Tips and Variations

This problem can be solved using other algebraic techniques, such as substitution or elimination.
The problem can be modified to involve different relationships between the man and his son, such as the man being twice as old as his son.
The problem can be extended to involve multiple generations, such as the man's son having a child of his own.

Real-World Applications

This problem has real-world applications in various fields, such as:

Demography: Understanding the age distribution of a population is crucial for demographic studies and policy-making.
Economics: The age structure of a population affects economic growth, labor force participation, and social security systems.
Healthcare: Understanding the age distribution of a population is essential for healthcare planning, disease prevention, and treatment.

Mathematics is a powerful tool that helps us solve problems, make predictions, and understand the world around us. This article demonstrated how algebraic equations can be used to solve a classic mathematical puzzle involving a man and his son. The present age of the son is 5, and the present age of the man is 35. We hope that this article has inspired you to explore the world of mathematics and its many applications.
A Man's Age and His Son: A Mathematical Puzzle - Q&A

In our previous article, we solved a classic mathematical puzzle involving a man and his son. We used algebraic equations to find the present ages of the man and his son. In this article, we will answer some frequently asked questions (FAQs) related to this problem.

Q: What is the relationship between the man's age and his son's age?

A: The man's age is seven times that of his son.

Q: How do we know that the man's age is seven times that of his son?

A: We are given this information in the problem statement.

Q: What is the equation that represents the relationship between the man's age and his son's age in 5 years?

A: The equation is 7x + 5 = 4(x + 5), where x is the present age of the son.

Q: How do we simplify the equation 7x + 5 = 4(x + 5)?

A: We simplify the equation by expanding the right-hand side, subtracting 4x from both sides, subtracting 5 from both sides, and dividing both sides by 3.

Q: What is the value of x, the present age of the son?

A: The value of x is 5.

Q: What is the present age of the man?

A: The present age of the man is 7x = 7(5) = 35.

Q: Can we solve this problem using other algebraic techniques?

A: Yes, we can solve this problem using other algebraic techniques, such as substitution or elimination.

Q: Can we modify this problem to involve different relationships between the man and his son?

A: Yes, we can modify this problem to involve different relationships between the man and his son, such as the man being twice as old as his son.

Q: Can we extend this problem to involve multiple generations?

A: Yes, we can extend this problem to involve multiple generations, such as the man's son having a child of his own.

Q: What are some real-world applications of this problem?

A: Some real-world applications of this problem include demography, economics, and healthcare.

Q: Why is understanding the age distribution of a population important?

A: Understanding the age distribution of a population is important because it affects demographic studies and policy-making, economic growth, labor force participation, and social security systems.

In this article, we answered some frequently asked questions related to the classic mathematical puzzle involving a man and his son. We hope that this article has provided you with a better understanding of the problem and its solutions.

Additional Tips and Variations

This problem can be used as a teaching tool to introduce algebraic equations and problem-solving techniques.
The problem can be modified to involve different relationships between the man and his son, such as the man being three times as old as his son.
The problem can be extended to involve multiple generations, such as the man's son having a child of his own.

Real-World Applications

This problem has real-world applications in various fields, such as:

Demography: Understanding the age distribution of a population is crucial for demographic studies and policy-making.
Economics: The age structure of a population affects economic growth, labor force participation, and social security systems.
Healthcare: Understanding the age distribution of a population is essential for healthcare planning, disease prevention, and treatment.

Mathematics is a powerful tool that helps us solve problems, make predictions, and understand the world around us. This article demonstrated how algebraic equations can be used to solve a classic mathematical puzzle involving a man and his son. We hope that this article has inspired you to explore the world of mathematics and its many applications.