please help me solving these questions

14) In order to save enough money for a down payment on a home, you deposit $1500 every 3 months for 5 years into an account that pays 8% interest compounded quarterly. You estimate you will need $25000 for your down payment, will you have enough after 5 years? 15) The Simpsons bought a new home in Springfield for $500,000. They paid 20% down and mortgaged the remaining over a 25-year amortization period. They agree to pay 5% interest compounded monthly. What is the monthly payment required to pay back the remaining mortgage? 16) You borrow $500 from your uncle and agree to repay the $500 plus $20 interest in 8 months. What interest rate are you agreeing to pay