Could you please show me how to solve this question?

Suppose you want to buy a new computer. It costs 1000 but since you don't have the money right now you consider different offers for 12-month financing options from different dealers. In all cases you are required to clear your debt by means of constant repayments at the end of every month. Which one is the best deal? Select one: O a. There is an extra charge of 30 to be payed upfront and the interest rate on the loan is 6% p.a. O b. There is an extra charge of 90 added to the loan but the dealer does not charge any interest. O c. There is an extra charge of 50 added to the loan and the interest rate is 5% p.a