1.  In an examination, a pupil's average marks were 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his History paper, his average per paper would have been 65. How many papers were there in the examination ?
A. 8
B. 9
C. 10
D. 11
E. 12

Answer: Option D

Explanation:

Let the number of papers be x. Then,
63x + 20 + 2 = 65x
(65x - 63x) = 22
x = 11