Answer:
5x-10x+100 or a simplified version: -5x+100 where x is the number of shirts
Step-by-step explanation:
5x is for every shirt they have to pay for and it adds to the cost
-10x is for every shirt they sell which decreases the total cost
100 is for the upfront cost of having the shirts professionally designed
hope this helped and if i misunderstood something lmk so i can change it :))