Correct Option: A

Let us assume the present age of Ram R, Shyam S and Mohan M.
5 years ago, Ram age = R - 5
5 years ago, Shyam age = S - 5
5 years ago, Mohan age = M - 5
According to question,
5 years ago, the average age of Ram and Shyam was 20 years,
(5 years ago, Ram age + 5 years ago, Shyam age) /2 = 20
(R - 5 + S - 5 )/2 = 20
R + S = 40 + 10 = 50 ................(1)
Now Again according to question,
Now , the average age of Ram, Shyam and Mohan is 30 years
(R + S + M)/3 = 30
R + S + M = 90
Pu the value of R + S from equation (1)
50 + M = 90
M = 90 - 50 = 40
The present age of Mohan = 40 years
10 years hence, the age of Mohan = 40 + 10 = 50 years