posted by econ .
(100 – 2Px + 1Py) (Px -20)
Now, take the derivative of the above with respect to Px to get the following first order condition :
100- 4 Px + Py +40 = 0
When i try to multiply and then take the derivative of the top part out I keep getting : -1860-4Px-19Py
What am I doing wrong??