Question

Five years ago a man was seven times as old as his son. Five years hence, the father will be three times as old as his son. Find their present age.

Answer 1

past age(5 years before)
Let the past age of son = x
Let the past age of father = 7x


So Present ages are x+5 and 7x+5

Future age(5 years after)
Future age of son = x+10
Future age of father = 7x+10

Given
age of father will be three times as old as his son after 5 years(future age)
7x+10 = 3*(x+10)
7x+10 = 3x+30
7x-3x = 30-10
4x = 20
x = 20/4
x = 5
7x = 35
we know present age is x+5 and 7x+5.
So
x+5 = 10
7x+5 = 40
So present age of son and father are 10 and 40