The ratio of Ramu and Gopu’s present age is 5 ∶ 8, and the ratio of Ramu and his son’s present age is 5 ∶ 2, and the ratio of Gopu and his son’s present age is 4 ∶ 1. If the Ramu is 30 years elder than his son, then find the age of Gopu’s son.
1
35 years
2
40 years
3
42 years
4
36 years
5
None of these