A. Subtract the difference between the two columns for two sets of numbers:
30-20 = 10
135 -110 = 25
40-30 = 10
160 - 135 = 25
So for every 10 t-shirts the total cost raises by 25
25 / 10 = 2.50 per t-shirt.
The starting cost is when 0 t shirts are sold.
110 - 50 = 60
The equation would be C = 2.50n + 60
( Multiply 2.50 by the number of t-shirts sold and then add the starting cost of 60).
B. See attached picture.
C. Using the equation from A replace n with 120:
C = 2.50(120) +60
C = 300 + 60
C = 360
It would cost $360.00
