A company distributes college logo sweatshirts and sells them for $40 each. The total cost function is linear, and the total cost for 90 sweatshirts is $2970, whereas the total cost for 280 sweatshirts is $6580. Write the equation for the total cost function C (x).

C (x) = 19x+1260

Step-by-step explanation:

For 90 sweatshirts

2970=90a+b

For 280 sweatshirts

6580=280a+b

Subtracting equation 1 from 2 then

6580-2970 = (280x-90x) + b-b

3610=190a

x=3610/190=19

2970=90 (19) + b

b=2970-90 (19) = 1260

Therefore, the equation will be

C (x) = 19x+1260