Rational Functions:

a)      Avg Cost of producing/selling  a shirt is         C(x)  / x  =    [ 120 + 2.5x - 0.0002x ]  /  x

b)    Avg Cost producing/selling 1200   shirts  =     [ 120  +  2.5 (1200) - .0002 (1200 ]  / 1200  =  3119.76 / 1200  ≈ $2.60

c)     Profit  at $7.98 =   1200  [7.98  - 2.60 ]  ≈ $ 6456

d) Let P be the price......so we want to solve this ;

7368  =  1200  [ P - 2.60 ]        divide both sides by 1200

[7368  / 1200]  =  P  -  2.60       add 2.60 to both sides

[ 7368 / 1200 ]  + 2.60  =  P ≈  $8.74