Answer:
Cost at which shop charge per surfboard in order to maximize monthly revenue is $300.
Step-by-step explanation:
Given : A surfboard shop sells 45 surfboards per month when it charges $500 per surfboard. For each $20 decrease in price, the store sells 5 more surfboards per month.
To find : How much should the shop charge per surfboard in order to maximize monthly revenue?
Solution :
A surfboard shop sells 45 surfboards per month,the store sells 5 more surfboards per month.
Let the surfboard sold be =

It charges $500 per surfboard, for each $20 decrease in price.
The cost at which they will be selling surfboard will be

Net revenue is

The maximum value of
is when

Therefore, The maximum value of
is


Cost at which shop charge per surfboard in order to maximize monthly revenue is
Substitute the value of x in cost




Therefore, Cost at which shop charge per surfboard in order to maximize monthly revenue is $300.