4. Alex has accumulated $8,600 in his credit card debt. The credit card company charges a 12% APR (compounded monthly). He knows he can pay part of his salaries after working part-time in a convenience store.

a. If Alex plans to settle the debt in 3 years without further expenditure with this credit card, what will the monthly payment that he needs to pay to the credit card company in order to fulfill this obligation? (7.5 marks)

b. Fortunately, his brother agrees to lend Alex money at 5% per annum. Alex plans to settle the debt with the credit card company now using the money borrowed from his brother, and start paying his brother on a monthly basis for 3 years. What will the monthly payment that he needs to pay his brother in order to fulfill this obligation? (7.5 marks)