Question

A is 20 years older than B. 5 years ago, A was 3 times as old as B. Find their present ages.

Answer 1

Let A’s presentage be x years
and B’s present age be y years

According to the question
x = y + 20
x - y = 20                            ...(1)

Five years ago,
x - 5 = 3(y - 5)
x - 5 = 3y - 15
x  - 3y = - 10                      ...(2)

Subtracting (1) and (2),
      x - 3y = - 10
  -   x - y  = 20    
     -    +    -        
         - 2y = - 30
             y = 15

From (1)
x = 15 + 20
x = 35
Thus, present ages of A and B are 35 years and 15 years.