Question

A father is 4 times as old as his son. In 20 years the father will be twice as old as his son.. Find their present ages

Answer 1

Father 40
Son 10
That is the answer

Answer 2

x = the age of his son now, then the age of the father is 4x.

In 20 years,

son's age = x + 20

father's age = 4x + 20

solve the equation for x:

4x + 20 = 2(x + 20)

4x + 20 = 2x + 40

2x = 20

x = 10

So the age of his son now is 10, and the age of the the father now is 40.