To evaluate the expression \( q - r \) for \( q = -2 \) and \( r = -8 \), you can substitute the values into the expression:
\[ q - r = -2 - (-8) \]
When you subtract a negative number, it is the same as adding its positive:
\[ -2 + 8 \]
Now perform the addition:
\[ -2 + 8 = 6 \]
So, \( q - r = 6 \).