The final cost of a bookstore purchase with a $5 coupon in a state that charges 8% sales tax is given by this expression. The variable x represents the amount of the purchase before the sales tax and the coupon are applied. 1.08(x−5) What does (x−5) represent?
a. the total charge after tax
b. the rate at which the total cost increases
c. the total charge before applying sales tax
d. the cost before applying the coupon