Activity a Has the Following Marginal (MB) and Marginal Cost

Activity A has the following marginal (MB) and marginal cost (MC) functions:
MB = 2,500 - 20A
MC = 500 + 30A
where MB and MC are measured in dollars.
-The optimal level of the activity is ________ units. At the optimal level of activity, marginal benefit is $_________ and marginal cost is $__________.
The total benefit (TB) and total cost (TC) functions for the activity are:
TB = 2,500A -10A²
TC = 500A + 15A²
where TB and TC are measured in dollars.