How to do this problem using the Financial calculator?

A store offers two payment plans. Under the installment plan, you pay 25% down and 25% of the purchase price in each of the next 3 years. If you pay the entire bill immediately, you can take a discount of 10% from the purchase price. Assume the product sells for $100. a-1. Calculate the present value of the payments if you can borrow or lend funds at an interest rate of 5 percent. (Do not round intermediate calculations. Round your answer to 2 decimal places.) PV of installment plan a-2 Which is a better deal? Installment plan Pay in ful b-1. Calculate the present value if the payments on the 4-year installment plan do not start for a full year. (Do not round intermediate calculations. Round your answer to 2 decimal places.) PV of installment plan