Question

A sporting goods store is having a 15% off sale on all items. Which functions can be used to find the sale price of an item that has an original price of x? You may choose more than one correct answer.
ƒ(x) = x - .15x
Sale = Original - 15
ƒ(x) = 1.15x
Sale = Original - .15(Original)
y = .85x

Answer 1

The answers are: 
ƒ(x) = x - .15x
Sale = Original - .15(Original)
y = .85x

Let sale price be f(x) and x be the original price. Discount was 15% = 0.15
f(x) = x - 0.15x

If f(x) is sale and x is the original, then:
Sale = Original - .15(Original)

Let sale price be y and original price x:
y = x - 0.15x
y = 1 * x - 0.15 * x
y = (1 - 0.15) * x
y = 0.85x