1. **State the problem:** Verify the equation $9 + (-2)(-6) = 21$ and understand the arithmetic involved. 2. **Recall the multiplication rule for negatives:** The product of two negative numbers is positive, so $(-2)(-6) = 12$. 3. **Substitute and simplify:** $$9 + (-2)(-6) = 9 + 12$$ 4. **Add the numbers:** $$9 + 12 = 21$$ 5. **Conclusion:** The equation $9 + (-2)(-6) = 21$ is correct because multiplying two negatives gives a positive, and adding 9 results in 21. This matches the label on the hypotenuse of the right triangle in the graph described.