In a row of Boys Mohan is 20th from the left and 12th from right end. Pratap is 15th from the right end in that row. How many boys are there between Mohan & Pratap?

2

It is clear,

Mohan is 12th from the right and Pratap is 15th from the right.

So, only 2 persons 13th and 14th position(p) from the right will be in between Mohan and Pratap

P₁ - P₂ - 1

15 - 12 - 1

= 2