Twenty students are standing in a row facing north. R is second to the left of P and is 11th from the left end. A is 5th from the right end. How many students are there between P and A?

2

As R is 11th from the left end and is 2nd to the left of P,

therefore P is 13th from the left.

So, total number of students between P and A are:

Total = 13 + 5 + x = 20

         18 + x  = 20

              x = 2