a store has a sale for 20% off. You decide to buy a $15 t-shirt.

(a) How much money will you save?

(b) How much money will you spend to the t-shirt?

(a) To calculate how much money you will save, you need to find 20% of the original price of the t-shirt.

20% of $15 = 0.2 * $15 = $3

So, you will save $3.

(b) To determine how much money you will spend on the t-shirt after the discount, subtract the savings from the original price.
$15 - $3 = $12

Therefore, you will spend $12 on the t-shirt.