A building contractor gives a $12,000 promissory note to a plumber who has loaned him $12,000. The note is due in 9 months with interest at 8%. six months after the note signed, the plumber sells it to a bank. If the bank gets a 9% return on its investment, how much will the plumber receive? Will it be enough to pay a bill for $12,364?

(According to my professor the plumber should receive $12,440.10 ; and this should be able to pay the bill.)

But the work for this answer is giving me a different solution.Please help!!!!!