If the retail price is $100 and it is marked down 20%, what is the new selling price?

To find the new selling price after a 20% markdown on a retail price of $100, you first need to calculate the amount of the discount.

A 20% discount means you take 20% of the original price of $100. Calculating this involves multiplying $100 by 0.20, which gives you a discount amount of $20.

Next, you subtract the discount from the original price:

$100 (original price) - $20 (discount) = $80.

This calculation shows that after applying the 20% markdown to the retail price of $100, the new selling price is indeed $80.