Question 32146
I'll do one; you do the other:
f(g(x))= f((3/4)x)=4/[(3/4)x - 2]
Domain? 
(3/4)x-2 cannot be zero.
So, if (3/4)x-2=0
        (3/4)x=2
          x=8/3
So, the Domain is all real numbers except x=8/3
Cheers,
Stan H.