First step:
Calculate f(5). Put x = 5 to the equation f(x) = x + 1:
f(5) = 5 + 1 = 6
Second step:
Calculate g[f(5)] = g(6). Put x = 6 to the equation g(x) = 3x - 2:
g(6) = 3(6) - 2 = 18 - 2 = 16
