Question

This year Alex’s age is 1/6 of his dads. Four years later, Alex’s age is 1/4 of his dads. How old is Alex and his dad this year?

Answer 1

This year:

dads: 36 years

Alex: 6 years

Explanation:

a = d/6

a+4 = (d+4)/4

a = Alex´s actual age

d = actual age of the dad

d/6 + 4 = (d+4)/4

4{(d/6) + 4} = d+4

4*d/6 + 4*4 = d+4

4d/6 + 16 = d + 4

4d/6 = d + 4 - 16

4d = (d-12)*6

4d = 6*d +6*-12

4d = 6d - 72

4d - 6d = -72

-2d = -72

d = -72/-2

d = 36

a = d/6

a = 36/6

a = 6

probe:

a+4 = (d+4)/4

6 + 4 = (36+4)/4

10 = 40/4