In a row of boys, Suresh is 7th from the left and Rohit is 12th from the right. If they interchange their positions, Suresh becomes 22nd from the left. How many boys are there in the row?

33

Suresh is 7th from the left and Rohit is 12th from the right

Now, if they interchange their positions, Suresh becomes 22nd from the left.

So, Suresh is 22 from left and 12 from right. (As, denoted by Rohit's position before the change of positions)

He has 21 boys before him and 11 boys after him.

Therefore, total number of boys = number of boys before him +Number of boys after him + Suresh

= 21+11+1 = 33

OR

⇒ position from right + position from left - 1 (to avoid double-counting)

= 22 + 12 - 1 = 33