THIS IS THE HARDEST WORK ON EART SOMEONE HELP ME

Acredit card advertises an annual interest rate of 23%. what is the equivalent monthly interest rate?

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

You just purchased two coins at a price of $670 each. because one of the coins is more collectible, you believe that its value will increase at a rate of 7.1 percent per year, while you believe the second coin will only increase at 6.5 percent per year. if you are correct, how much more will the first coin be worth in 15 years?