If $3 n=9+9+9$, then $n$ equals
(A) 3
(B) 6
(C) 18
(D) 9
(E) 27
Since $3 n=9+9+9=3 \times 9$, then $n=9$.

Alternatively, we could note that $9+9+9=27$ and so $3 n=27$ which gives $n=\frac{27}{3}=9$.

ANSWER: (D)