Cait purchases a $20 item at a store. she uses a coupon to receive a 15% discount and she pays 6% on the item. she calculates the total cost, in dollars, of the item using the expression shown.

cait's expression: (1.15)(1.06)(20)

part a: describe the error in the expression cait used for her calculation.

part b: show or explain how you would calculate the total cost of cait's purchase.