g(x)=4-2x
1) g(f(2))
2) G(a-1)

how do u plug this in?
and solve this for me please

For 1), you simply replace the 'x' in the first equation with f(2):

g(f(2)) = 4 - 2f(2)

For 2) there apparenly is a different function called 'G(x)' which you have not defined for us.