To evaluate the expression \( \frac{n}{p} \) for \( n = -18 \) and \( p = -6 \), we can substitute the given values into the expression:
\[ \frac{n}{p} = \frac{-18}{-6} \]
Now, simplify the fraction:
\[ \frac{-18}{-6} = 3 \]
Thus, the simplified answer is:
\[ 3 \]