If the sum and difference of two numbers are 5 and 10 respectively, then the difference of their square is: Pick:  A) 50  B) 28  C) 160  D) 180  E) 18

Rationale: "let the numbers be x and y . then , x + y = 5 and x - y = 10 x 2 - y 2 = ( x + y ) ( x - y ) = 5 * 10 = 50 . answer : a"
Answer: A