A sale price with the original price missing signals a reverse percent change. A discount is measured against the original price, so first find what percent remains and set that part of the unknown original equal to the sale price. Then use a Desmos regression to solve. Taking another percent off the sale price moves in the wrong direction.
Hints
- Hint 1
A discount is the part removed from the original price. The sale price is the part left. What percent remains after is removed from the full ?
- Hint 2
The base is the amount a percent is taken of. Here, that's the unknown original price, not the sale price. If you call the original , what does of equal?
Step-by-step
Work backward from the sale price
Step 1Find the percent left
represents the full original price. The sale removes of it, so subtract to find the percent left:
- Step 2
Write the sale-price equation
Let be the jacket's original price. The base is the amount the percent acts on, so of the unknown original equals the $68 sale price:
Don't take of $68: the discount was taken from the original price.
- Step 3
Solve for the original price
Type in Desmos. A regression finds the value of that makes the two sides match; Desmos reports under PARAMETERS. So the jacket's original price was $80. Choice C.