1. m = aa means m is divisible by 11, but n = ? do not know.
If m = aa, doesn't that force n to be a mutiple of 11 since the original equation says that m-n is a multiple of 11. Ex: m=55-n=11X, n = bb, so is a multiple of 11, which means X is an integer
m - n = 11x, but we do not know whether x is an integer. in fact thats the question.
suppose, m = 44 and n = 14, then m - n = 30
so 30 = 11x
x = 30/11, which is not an integer
if n = 22, then m-n = 44-22=22,
22 = 11x
x = 2, which is an integer.
therefore, 1 is not suff.