In coaching institute B, the total number of students who have enrolled from schools P and R together is what percent less than the ‘total number of students enrolled from schools Q and S together ?

Number of students who have enrolled from coaching institute B from schools P = 24% of 100 = 24
Number of students who have enrolled from coaching institute B from schools Q = 33% of 100 = 33
Number of students who have enrolled from coaching institute B from schools R = 21% of 100 = 21
Number of students who have enrolled from coaching institute B from schools S = 22% of 100 = 22

Number of students who have enrolled from coaching institute B from schools P and R = 24+21 = 45
Number of students who have enrolled from coaching institute B from schools Q and S = 33 + 22 55

55-45/55 = 18.1818 =18 2/11%
Option C is the correct answer.