题目内容：

英文的导数数学题,求步骤,解题过程
(1 pt) The total profit (in dollars) from the sale of charcoal grills is
P(x)=30x-0.3x^2-215
(A) Find the average profit per grill if 40 grills are produced.
Ave. profit =
Find the marginal average profit at a production level of 40 grills.
(B) Marginal average profit =
Use the results from parts (A) and (B) to estimate the average profit per grill if 41 grills are produced.
(C) Estimated average profit =