An investment yields an interest payment of $225 each month. If the simple annual interest rate is 9%, what is the amount of the investment?	Choose the correct choice:
A) $ 30,000 B) $ 30,400 C) $ 31,300 D) $ 32,500 E) $ 35,100

Rationale: "let the principal amount = p simple annual interest = 9 % simple monthly interest = ( 9 / 12 ) = ( 3 / 4 ) % ( 3 / 4 ) * ( p / 100 ) = 225 = > p = ( 225 * 4 * 10 ^ 2 ) / 3 = 75 * 4 * 10 ^ 2 = 300 * 10 ^ 2 = 30000 answer a"
Answer: A