Question 290378
You want the vertex.
The x component or n component will be the number of paints with maximum profit P(n)
what is the x component of the vertex -b/2a
-80/2*-2=80/4=20
plug 20 in  for n and solve and that will give you the max of the parabola which should come out to 770

Everyone here wants help.
I generally avoid the problems with begging.