If a, b, c, and d are integers; w, x, y, and z are prime numbers; w < x < y < z; and (wa)(xb)(yc)(zd)=660(wa)(xb)(yc)(zd)=660, what is the value of (a + b) – (c + d)?  Choices
A) – 1	B) 0	C) 1	D) 2	E) 3

Rationale: 660660 = 2 ^ 2 x 3 ^ 1 x 5 ^ 1 x 11 ^ 1 w < x < y < z = 2 < 3 < 5 < 11 so , can can say - w = 2 x = 3 y = 5 z = 11 hence a = 2 , b = c = d = 1 ( a + b ) – ( c + d ) will be ( 2 + 1 ) – ( 1 + 1 ) = 1 answer will be ( c )
Answer: C