Answer:
a).
[tex](fog)(x) = f(g(x)) \\ = (3x + 1) + 4 \\ = 3x + 5 \\ [/tex]
b).
[tex](gof)(x) = g(f(x)) \\ = 3(x + 4) + 1 \\ = 3x + 12 + 1 \\ = 3x + 13[/tex]
c).
[tex](fog)( - 2) = 3( - 2) + 5 \\ = - 6 + 5 \\ = - 1[/tex]
d).
[tex](gof)( - 2) = 3( - 2) + 13 \\ = - 6 + 13 \\ = 7[/tex]
I hope I helped you^_^
