Which of the following pairs of functions are inverses of each other?
a f(x)=x-8/4+9 and g(x)=4(x+8)-9
b f(x)=3(x/2)-4 and g(x)=2(x+4)/3
c f(x)=3(2/x)-10 and g(x)=x/6+10
d f(x) =4(x-12)+2 and g(x)=x+12/4-2