If the sum and difference of two numbers are 20 and 8 respectively, then the difference of their square is:	Select:
A) 12  B) 28  C) 160  D) 180  E) 18

Rationale: "let the numbers be x and y . then , x + y = 20 and x - y = 8 x 2 - y 2 = ( x + y ) ( x - y ) = 20 * 8 = 160 . answer : c"
Answer: C