Question

A father is 38 years old. his sons are 13 and 5 years old, and his daughter is 8 years old. In how many years will the father be the same age as his children put together?

Answer 1

6 years

Explanation:

So each person's age can be represented as a linear equation, since each year our age increases by 1. It can be represented in the slope-intercept form: y=mx+b. The slope in this case is going to be 1, since the time is going to be years, and each year everyone's age goes up by 1 (of course if you're still alive...) and y-intercept in this case represents their current age.

So the father can be represented as: y=x+38

The sons can be represented as: y = x+13 and y=x+5

The daughter can be represented as: y=x+8

So adding up all his children you get:

(x+13)+(x+5)+(x+8)

This gives you the equation:

3x+26

Now set this equal to the father's age to solve for x (in this context it's years)

3x+26=x+38

Subtract from both sides

2x+26=38

Subtract 26 from both sides

2x=12

Divide both sides by 2

x=6

So in 6 years the father will be the same age as his children put together