PRICE HOW MANY COST
40 150
40-1 150+5
40-2*1 150+2*5
40-3*1 150+3*5 (40-3*1)(150+3*5)
.
.
.
40-n 150+5n (40-n)(150+5n)
One way to continue this way is to use n for how many $1 increases, and look at the
cost expression for finding the maximum revenue. (Quadratic in n).