Question

5 years ago, the average age of ram and shyam was 20 years. now the average age of ram, shyam, and mohan is 30 years. what will be mohan's age 10 years hence?

Answer 1

Let R,S and M be Ram's, Shyam's and Mohan's ages respectively.
Given
5 years ago, the average age of ram and shyam was 20 years
$$\begin{gathered} \frac{(R-5)+(S-5)}{2}=20 \\ R+S-10=40 \\ R+S=50...\left(1\right) \end{gathered}$$
now the average age of ram, shyam, and mohan is 30 years.
$$\begin{gathered} \frac{R+S+M}{3}=30 \\ (R+S)+M=90 \\ 50+M=90(from(1\left)\right) \\ M=40 \end{gathered}$$
After 10 years, Mohan's age = 40+10=50 years