I’ll give the Brainliest to who answers this question with a reasonable explanation. If Jan can buy 12 copies of a certain book for $40, what is the unit rate for cost per copy? How much would it cost her to buy 18 copies at the same rate?

Thank you!

Which account has the highest effective annual interest rate? not necessary but show how you got your answer.a. account 1: interest is compounded quarterly at an annual rate of 4.20%.b. account 2: interest is compounded monthly at an annual rate of 4.15%.c. account 3: interest is compounded semiannually at an annual rate of 4.10%d. account 4: interest is compounded annually at a rate of 4.25%.