C in c(x)=0

Brampton Winter Sports manufactures gas-powered snowblowers at a cost represented by the cost function C(x) = 500 + 5x + 0.01x, where x is the number of snowblowers manufactured, in thousands. The demand for snowblowers in Brampton is p(x) = 10 - 0.002x. (a) Find the revenue function, and the marginal revenue function. (b) Find the profit function, and the marginal profit function. (c) Find the marginal profit at a production level of 150 000 snowblowers