Revenue = 200 * 40 000 = 8 000 000 presently
x = number of 10 dollar increases from 200 dollars
Revenue = (200+ 10x)(40 000 - 400x)
= 8 000 000 - 80 000x + 400 000x - 4000x^2
= -4000 x^2 +320 000x + 8 000 000
Divie thru by 4000 to make it easier to work with
- x^2 + 80x +2000 max will occur at x = - b/2a = - 80/(-2) = 40
or 40 ten dollar increases would make tix 600 dollars