Wherever you see x in f(x), substitute in g(x).
So f(g(x)) = (g(x))² + 3
But what's g(x)?
g(x) = (x + 2)/x
So the answer would be ( (x+2)/x )² + 3
Which could simplify to (x+2)² / x² + 3 = (x² + 4x + 4)/x² + 3
Sorry if I made a mistake somewhere.
Hope this helped!