Question 3864
 Let M = 10a + b, then N = 10 b+ a,

 So M + N = 11 a + 11 b = 11 (a+b) , this means
 M + N should be a multiple of 11.
 
 Note amont these 5 integers 
 (A) 181   (B) 163
  are not multiple of 11.

 Hope you can see by direct view without any calculations.

 In fact an ineger is a multiple of 11 if and only if the
 difference of the sum of odd digits and the sum even digits is a multiple 
 of 11 . e.g. 286, 8294,73524.

 Kenny