Bunuel wrote:
Consider the binary operation # defined by a#b = 10a + b, where the operations on the right side of the equal sign denote the standard arithmetic operations. Suppose M = x#y and N = y=x, where x and y are positive integers, which of the following must be a factor of M + N ?
(A) 14
(B) 11
(C) 10
(D) 9
(E) 6
I believe N = y#x here
Then M+N becomes 11a+11b
B
