Question

Allison is saving money to buy a new phone that costs $600 by selling her graphic designs. She is using an app to manage her sales, but it keeps a fraction of each sale. Her net pay is modeled by the function P(x) = x2 + 18x – 160, where x represents the number of sales. How many sales does Allison to make to earn $600?

9 sales
20 sales
38 sales
841 sales

Answer 1

Answer: 20 sales.

Proof of validity is shown below.

Answer 2

20 sales.

Explanation:

p(x) = x² + 18x – 160

Here p(x) represents the net pay.

Given that p(x), net pay is $600

x² + 18x – 160 = 600

x² + 18x – 160 - 600 = 0

x² + 18x – 760 = 0

x² +38x - 20x - 760 = 0

x(x+38) - 20(x+38) = 0

(x-20)(x+38) = 0

x = -38, 20

x = 20

Therefore, she makes 20 sales in order to make $600.