For this case we have:
Cost of manufactures of T-shirts 
where x represents the number of T-shirts
Part A:
Substituting
in the total cost equation you have to:

Thus, the cost of 8 shirts will be 
Part B:
If
then

Thus, the cost of 12 shirts will be 
Answer:

This is a square root meaning whatever number multiplied by itself equals it’s square root. The answer would be 4 on the outside and 3 on the inside
I'm not completely sure about this answer but here is what I got: 100•15=1500 for one day of the food booth. 50•22=1100 one day for the game booth. 1500+(x9) and 1100+(x8). (1500+x)+(1100+x)=x