well a few weeks ago I asked for help with my maths homework, too me they have stepped it up a notch - i have been attending lectures and doing the readings but still kinda struggling as he hasnt given us examples too see the workings(the easiest way I learn new things). The homework is due tommorow and was hoping someone could help again, I'd be incredibly grateful

The cost function of a firm is given by C(Y) = (2/3)Y3 - 8Y2 + 48Y + 20, and the revenue function is given by R(Y) = 40Y - 3Y2.

(a) What is the profit function?

(b) Since marginal revenue is given by MR(Y) = â??R/â??Y, determine an expression for marginal revenue. Draw a graph of MR(Y).

(c) Since marginal cost is given by MC(Y) = â??C/â??Y, determine an expression for marginal cost. Draw a graph of MC(Y). At what value of Y does MC achieve a minimum?

ok for a) I got profit is equal too = -2Y^2+10Y-8

I'm unsure if I've taken it several steps too far as profit is equal too revenue minus cost..

assuming a is right I'm still stuck on b, havent even bothered with c