Step-by-step explanation:
To answer a question like this, refer to the definitions of the functions:
(f-g)(200) is ...
... the difference between the amount of money a cell phone screen is being sold for and the cost of production, when 200 screens are being manufactured.
__
The numerical value of (f-g)(200) is ...
f(200) -g(200) = (3·200 +5000) -(20·200 -400) = 5600 -3600
(f-g)(200) = 2000