The number of pair of positive integers whose sum is 99 and HCF is 9 is
2
3
4
5
Correct Option: D
Let the numbers be 9x and 9y where x and y are prime to each other. According to the question, 9x + 9y = 99 ⇒ 9(x + y) = 99 ⇒ x + y = 11 Possible pairs = (1, 10) (2, 9), (3, 8), (4, 7), (5, 6)