In an examination, Shreya's average marks were 63 per paper. If she had obtained 20 more marks for her Maths paper and 2 more marks for his Social paper, her average per paper would have been 65. How many papers were there in the examination?
11
Let the numbers of papers be x.
Then, 63x + 20 + 2 = 65x (or) 2x = 22 (or) x = 11.