Zoe found a sweatshirt that she wanted at jcpenny when she went shopping the other day. it was 30% off. what was the original cost if the sale price was 21$

The sale price was 30% off the original price, which means it was on sale for 70% of the original cost (100% - 30% = 70%)

To find the original cost, divide the sale price by the percent of the original cost:

21 / 0.70 = 30

The original price was $30

check:

30 x 0.3 = 9 (amount of discount)

30 - 9 = 21 (sale price)