exponent problem 
Can anyone answer this question?  $$3^{n+2} + (3^{n+3} - 3^{n+1})= ?$$ 

I really want to know how to solve this one, our solution can't seem to agree with the problem's answer thank you!

If the answer is $3/8$ probably the question is:
$$\frac{3^{n+2}}{3^{n+3}-3^{n+1}}=\frac{3^2\cdot3^n}{3^3\cdot3^{n}-3\cdot3^{n}}=\frac{3^2\cdot3^n}{3^n(3^3-3)}=\frac{3^2}{27-3}=\frac{3}{8}$$
