Your answer should be 19>n+3
I don't know if you want the whole x+2 on the bottom or not, but I will put it on the bottom for now.
Replace x with (3+h)
f(3+h)=1/[(3+h)+2]
Now if it's supposed to be JUST x in the denominator...
Replace x with (3+h)
f(3+h)=1/(3+h)+2
Best wishes!