Can someone please help me with this algebra

Acar dealership pays you 5% commission on your first $10,000 on car sales and 8% commission on the sale amount over $10,000 if you sold a $12,000 car how much is your commission

Write a function that matches the description. a cosine function has a maximum of 5 and a minimum value of -5. f (r) =

You deposit $5000 each year into an account earning 3% interest compounded annually. how much will you have in the account in 30 years?