Mr rosenthal bought 15 computer disks and a carrying case for 28.50 if the carrying case cost 6.75 w

Mr rosenthal bought 15 computer disks and a carrying case for 28.50 if the carrying case cost 6.75 what was the cost of each disk

Figure out how much he has left over after purchasing the carrying case:
28.50 - 6.75 = 21.75

Now, figure out the price per disk:
21.75/15 = 1.45