Functions

I am not going to do the whole question for you but i will try to explain.
If g(x)=3*t - 6
then g(2) would equal 3*2 - 6 = 0
g(-4) = 3*(-4) - 6 = -18
g(a) = 3*a - 6

Just replace the original thing in the bracket with the new thing in the bracket.