Hi guys, I'm think im missing a step here:

cost in pounds =C=500+10X*(x=no. units produced)

revenue in pounds =R=150X - 3X^2

I work out the weekly profit by subtracting C from R, which =P.

I need to show that, in terms of the number of units produced (X), the weekly profit is given by,P =140X - 500 - 3X^2.

So far I havedone P = R - C

p = (150X - 3x^2) -(500 + 10X)

= 140X - 3X^2 - 500

Have i shoen that in terms of X as I needed to, as my 500 and 3X^2 are the other way round....This is what confuses me.

Any light you could shed on this would be great,

Thank you.