During a sale mohamed discounted all shirts in his store by a certain percent . if the shirts normally priced at $15 were marked down to $12 , what would be the marked-down price of a shirt normally priced at $20 ?

To start, we need to find the percent decrease of the $15 shirt. The price decreases by 3 dollars, from the original $15. 3 is 1/5 of 15 so the shirt was discounted 1/5, or 20%. Next, we need to discount the $20 shirt by the same amount. 20% is equal to one fifth, so just take off one fifth of the $20 for the shirt. 1/5 of 20 is four, so 20-4= 16. The $20 shirt would now cost $16.