Since the first fifty shirts are 10 bucks each, you would subtract that 50 from 125, which gives you 75. Now with that 50,you would multiply it by 10, which is 500. Now put that 500 to the side, and do your remaining 75 times the 8 dollars that is now being charged. You should get 600. Finally, you add the 500 that you put aside and the 600 to get 1100.
