The sum of two numbers is 30 and their difference is 10. Find their product. Choose the correct choice from the following choices.
A) 104  B) 114  C) 315  D) 200  E) 335

Rationale: let the numbers be x and y . then x + y = 30 and x - y = 10 x = 20 ; y = 10 xy = 20 * 10 = 200 answer : d
Answer: D