I have a question that I'm almost embarrassed not to know the answer to.

How do you work the following problem, and is the correct answer $50:

If something costs $40, and they took 20% off, what is the original price.

Thank you
Kevin

Hi Kevin,

If the seller took off 20% to arrive at $40 then $40 is 80% of the original price. What remains now is to read the english sentence and "mathematize" it. The sentence is

Eighty percent of the original price is $40.

Percent is per one hundred so 80 percent is ⁸⁰/₁₀₀ = 0.80. The word "of" signifies multiplication like one quarter of 20 is 5, ie ¹/₄  20 = 5. In the english sentence "is" is the verb and in a mathematical equation the verb is the equal sign. Thus

Eighty percent of the original price is $40.

becomes

 0.80 (the original price) = $40

and hence

the original price = ^$40/_0.80 = $50

Penny