Answer:
p'(x) = -0.12x +7.7
Step-by-step explanation:
Profit is the difference between revenue and cost:
p(x) = r(x) -c(x)
p(x) = (-0.06x^2 +8x) -(0.3x +240) = -0.06x^2 +7.7x -240
Marginal profit is the derivative of this function:
p'(x) = -0.12x +7.7
