If the average of the ages of Rakesh and Mohan is 15, average of the ages of Mohan and Ramesh is 12 and the average of the ages of Rakesh and Rameh is 13, then the age of Mohan, is?

Let ages of Rakesh, Mohan and Ramesh be R, M and r, respectively .
Then, R + M = 15 x 2 = 30.......(i)
M + r = 12 x 2 = 24 ........(ii)
r + R = 13 x 2 = 26 ..... (iii)
Adding Eqs. (i), (ii) and (iii), we get
2(R + M + r) = 30 + 24 + 26 = 80
⇒ R + M + r = 40
Subtracting Eq. (iii) from Eq. (iv), we get
M = 40 - 26 = 14