Tomas needs to borrow $3900 so he can repair damages to his car. He plans to pay

Question:

Tomas needs to borrow $3900 so he can repair damages to his car. He plans to pay the loan back in full in 5 months using his income tax refund. He can go to a finance company that will charge him 18% or to his uncle, who has agreed to charge him 9%. Find the difference in the interest charges