Check my work please!!

Did I do everything right?

f(x) = x + 3/ 5
y = x +3/ 5
5 * x = y + 3/ 5 * 5
5x - 3 = y + 3 - 3
5x - 3 = y
f^-1(x) = 5x - 3

SECOND:
g(x) = 7x - 4
g(f(x)) = 7(f(x)) - 4
g(f(x)) = 7(x+3/ 5) - 4
g(f(x)) = 7(x+3/ 5) * 5 - 4 * 5 = gf * 5
7(x + 3) - 20 = 5gf
7x + 21 - 20 = 5gf
7x + 1 = 5gf
7x +1 - 1 = 5gf - 1
7x = 5gf - 1
7x/7 = 5gf - 1/ 7
x = 5gf - 1/ 7