Which describes the steps that can be used to solve this problem?

flora bought 6 paperback books at the book sale. each book cost $4. she gave the cashier $30. how much change would flora get?

a. calculate the amount of money that 6 books cost. divide that number by the amount of money flora gave the cashier.

b. calculate the amount of money that 6 books cost. subtract that amount from the amount of money flora gave the cashier.

c. calculate how much one book costs. multiply that number by the amount of money flora gave the cashier.

d. calculate the amount of money that 6 books cost. add that number to the amount of money flora gave the cashier.

i will mark as brainliest.