if the function f(x) is expressed in the form f of g

Question

If the function h(x)=1/x+3 is expressed in the form f∘g with g(x)=x+3, then find the function f(x).

f(x)= 

Answer 1

f(x) = 1 / x

g(x) = x + 3

f(g(x)) = 1 / (x + 3)