use the amortization formula

(1) What monthly payment is needed to pay off a loan of $500 amortized at 12% compounded monthly for 2 years?

(2) A couple has decided to purchase a $100,000 house using a down payment of $20,000. They can amortize the balance at 8% for 25 years. What is their monthly payment?

(3) How long will it take to exhaust an IRA of $100,000 if you withdraw $2000 every month? Assume a rate of interest of 5% compounded monthly.

Could I get some help please?