SATMathematics Practice Test 1

Let x be the original price of the computer, in dollars. The discounted price is 20 percent off the original price, so x−0.2x=0.8x is the discounted price, in dollars. The tax is 8 percent of the discounted price, so 0.08(0.8x) is the tax on the purchase, in dollars. The price p, in dollars, that Alma paid the cashiers is the sum of the discounted price and the tax: p=0.8x+(0.08)(0.8x) which can be rewritten as p=1.08(0.8x).Therefore,the original price, x, of the computer, in dollars, can be written as

P

(0.8)

(1.08) in terms of p
Choices A, B, and C are incorrect; each choice either switches the roles of the original price and the amount Alma paid, or incorrectly combines the results of the discount and the tax as 0.8 + 0.08 = 0.88 instead of as (0.8)(1.08).