Answer:
$45 is the price that provide the maximum revenue
Explanation:
Let x be the number of times the price increase
A company can sell 2000 magazine subscriptions , for each price increase they sell 200 few subscriptions. (2000-200x) for x times increase.
for each $5 increase, the cost becomes 40+5
For x times increase the cost becomes 40+5x
Revenue is cost time the number of magazines



a=-1 and b = 2
To get maximum revenue find out the vertex

price is 40+5x= 40+5(1)= 45
so $45 is the price that provide the maximum revenue