Question 44396
Let "x" be the number of $5 increases.
Then Revenue = (45+5x)(200-4x)
             = 45(200)+1000x-180x-20x^2
             = -20x^2+820x+9000
Maximum Revenue occurs when 
    x=-b/2a =-(820)/-40=20.5
When x=20.5, Revenue = $17405
Cheers,
Stan H.