Question 1·Easy·Percentages
A jacket originally costs $120. It is on sale for 15% off the original price. What is the sale price of the jacket?
For percent discount problems, first decide whether you want to find the discount amount or multiply by the remaining percentage. Either compute the discount as original × discount_rate and subtract from the original, or multiply directly by 1 − discount_rate (for 15% off, use ). Converting the percent to a decimal early and doing one clean calculation helps you avoid mixing up subtracting the percent versus subtracting the dollar amount.
Hints
Translate the percent into a decimal
Change 15% into a decimal before multiplying by the original price. What decimal is equal to 15%?
Find the discount amount first
Multiply the original price, $120, by the decimal form of 15% to find how many dollars are being taken off.
Apply the discount to the original price
Once you know how many dollars are discounted, subtract that amount from $120 to get the sale price.
Desmos Guide
Calculate the sale price with a single expression
In Desmos, type 120*(1-0.15) or 120*0.85 to represent taking 15% off the original price. The value that Desmos outputs is the sale price.
Step-by-step Explanation
Understand what 15% off means
"15% off" means you reduce the original price by 15% of that price. So you first need to find 15% of $120, then subtract that amount from $120.
Find 15% of $120
Convert 15% to a decimal: . Then multiply:
So the discount amount is $18.
Subtract the discount from the original price
Now subtract the discount from the original price:
So the sale price of the jacket is $102, which corresponds to choice B.