Plug in 10 for x in h(x) then simplify
h(10)=2(10)-8
h(10)=20-8
h(10)=12
h(10) is 12 so put 12 in for g(x)
g(h(10))=12-4
g(h(10))=8
Here’s everything together
g(h(10))=(2(10)-8)-4
=(20-8)-4
=(12)-4
=8
This is what I’ve always done. I can’t really tell what your answers are so sorry if this isn’t right at all.