25.5 dollars.
Graph the equation and see where the highest point on the graph is. The x coordinate is the price and the y coordinate is the profit.
I think i know how to solve it but i would take a couple of minutes
For example on -9+6 you would start at -9 and go right 6 times over and what you land on is your answer<span />
Point slope form, y-y1 = m(x-x1)
Here, y1 = -1, x1 = 4, m=8
so, it would be: (y+1) = 8(x-4)
