Answer:
Yes
They are inverse functions
Explanation:
If two functions f(x) and g(x) are inverses of each other then
f(g(x)) = x and
g(f(x)) = x
We have f(x) = x - 9 and g(x) = x + 9
f( g(x) ) can be found by substituting the expression for g(x) for every x occurrence in f(x)
f( (g(x) ) = (x + 9) - 9 = x
g( f(x) ) = (x - 9) + 9 = x
So indeed f(x) and g(x) are inverses of each other