1. The problem is to find the result of the expression $-15 - 7$. 2. This is a subtraction problem involving negative numbers. 3. Subtracting a positive number from a negative number means moving further left on the number line. 4. We can rewrite the expression as $-15 + (-7)$ to see it as addition of two negative numbers. 5. Adding two negative numbers results in a more negative number: $$-15 + (-7) = -(15 + 7) = -22$$ 6. Therefore, the answer is $-22$.