First combine the two functions so that we have an equation for a to solve:
G(h(a)) = (3^x)^3 + 1 = 3^(3x) + 1 = 244
which gives
3^(3x) = 243
Now we can use logarithms in order to solve the equation
log(3^(3x)) = log(243)
but log(3^(3x))=3x*log(3)
so we have x = (log(243))/(3*log(3))
and if we enter this into a calculator we find that x=5/3