Can someone please explain to me how to get the answer for the question is the picture? I don't get it at all, and the internet isn't helping. Please explain the way you got the answer

Answer:
The original price of the item is $28.
Step-by-step explanation:
So to find the original price, we have to divide the sale price by the result of one minus the discount in percentage form.
So:
First convert 25% to a decimal, 0.25.
OP(original price) = 21 ÷ 1 - 0.25 =
1 - 0.25 = 0.75
21 ÷ 0.75 = 28.