A. It is given that the first one is the cost. Therefore, f(x)=100+3x. B. g(x)=8x is the revenue because it is said to be one. C. You can use f composition of g. This basically means that you can combine the system. D. Whenever there is x replace it with the other function f(g(x))= 100+3(8x) f(g(x))= 100 + 24x