Profit, P, in dollars from the sale of x MP3 players is given with the following function.

P(x) = R(x) - C(x)

WhereR(x) = x(350 - 0.000325 x^2)

andC(x) = 0.00015 x^3 + 100x

DETERMINE AN EQUATION FOR THE FUNCTION.

I.E if x = 100 then R = 34675 and C = 10150 so P = 24525

Theback of the bookgives me the answer as the equation being

P(x) = 250x - 0.000475 x^3.

Yes this works of course it works it gives me the same answer of 24525.

I just don't understand how the back of the book got that equation.

Is there anyone who can explain how that equation was created?