Question: User: $-2x-9y=-9$ and $-x-y=-8$.
1. **State the problem:** Solve the system of linear equations:
$$-2x - 9y = -9$$
$$-x - y = -8$$
2. **Formula and rules:** We can use substitution or elimination to solve this system. Here, we'll use substitution.
3. **Isolate a variable:** From the second equation:
$$-x - y = -8 \implies x + y = 8 \implies x = 8 - y$$
4. **Substitute into the first equation:**
$$-2(8 - y) - 9y = -9$$
5. **Simplify:**
$$-16 + 2y - 9y = -9$$
$$-16 - 7y = -9$$
6. **Isolate $y$:**
$$-7y = -9 + 16$$
$$-7y = 7$$
$$y = \frac{7}{-7} = \cancel{\frac{7}{\cancel{-7}}} \times \cancel{-1} = -1$$
7. **Find $x$:** Substitute $y = -1$ into $x = 8 - y$:
$$x = 8 - (-1) = 8 + 1 = 9$$
8. **Solution:**
$$\boxed{(x, y) = (9, -1)}$$
This means the solution to the system is $x=9$ and $y=-1$.