Aubrey found an awesome deal on a new backpack when she went back-to-school shopping. The backpack originally cost b dollars, but it was on sale for 75% off.
To calculate the price of the backpack after the discount, we need to find 75% of the original price and subtract it from the original price.
Discount = 75/100 * b = 0.75b
New price = Original price - Discount = b - 0.75b = 0.25b
Therefore, Aubrey paid 0.25b dollars for the backpack.