Question

Cait purchases a $20 item at a store. She uses a coupon to receive a 15% discount, and she pays a 6% sales tax on

the item. She calculates the total cost, in dollars, of the item using the expression shown.

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Cait's Expression

(1.15)(1.06)(20)

A. Describe the error in the expression Cait used for her calculation.

B. Show or explain how you would calculate the total cost of Cait's purchase.

Type your answers in the space provided.

Answer 1

A. Cait treated the discount as an increase

B. (20) (1.06) (0.85)

Explanation:

Hi, Cait treated the discount as an increase.

Cait multiplied the price (20) by the tax percentage (increase) 1.06

Since the sale tax increase is 6% and it is added to the price we have to express it in decimal form (6/100=0.06) and add it to 1.

20 (1 +0.06) = 20 (1.06)

The coupon discount is subtracted to the price. So, the correct form is:

15/100= 0.15

20 (1-0.15) = 20 (0.85)

Instead of this, Cait expressed the percent discount as a percent increase .

20 (1+0.15) = 20 (1.15)

The correct form is (20) (1.06) (0.85)