Bob Purchases a New Smart Phone for $500

Multiple Choice

Bob purchases a new smart phone for $500.The terms for the purchase are 2/30 n/90.If Bob would need to borrow money to take advantage of the discount,at what simple interest rate r will he be indifferent as to borrowing to take advantage of the discount versus paying the full balance when due? (Assume exact interest) .

A) 12.41%
B) 8.28%
C) 12.24%
D) 8.11%