If the sum and difference of two numbers are 20 and 10 respectively, then the difference of their square is: Answers:
A) 12
B) 28
C) 160
D) 200
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 * 10 = 200 . answer : d"
Answer: D