Question 550376
son be x years
father = 4x


after 3 years
son will be x+3 
father will be 4x+3

4x+3 = 3(x+3)

4x+3= 3x+9
4x-3x=9-3
x=6

son's ge = 6 now
father's age = 24 years

3 years ago
son = 3years
father = 21 years