The standard form: Ax + By = C
y = 90 - 15x <em>add 15x to both sides</em>
<h3>15x + y = 90</h3>
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:

Answer:
$90.75
Step-by-step explanation:
103*100=(13.5%+100%)*x
10300=113.5x
x=10300/113.5
x=90.74889868
x=$90.75