Question

Ethan is 40 years old. His son is 12 years old.

Answer 1

20 years in the future......

Answer 2

40-x / 12-x = 5
40-x = 5 * (12-x)
40-x = 60 - 5*x
5*x-x = 60 - 40
4*x=20
x=5

It was 5 years ago. Ethan was 35 and son was 7.