1. **State the problem:** Solve the system of linear equations:
$$-2x - y = -9$$
$$5x - 2y = 18$$
2. **Formula and method:** We will use the substitution or elimination method. Here, elimination is convenient.
3. **Eliminate one variable:** Multiply the first equation by 2 to align coefficients of $y$:
$$2(-2x - y) = 2(-9) \Rightarrow -4x - 2y = -18$$
4. **Write the system now:**
$$-4x - 2y = -18$$
$$5x - 2y = 18$$
5. **Subtract the first from the second:**
$$\cancel{-4x} - 2y - (\cancel{-4x} - 2y) = 18 - (-18)$$
$$5x - 2y - (-4x - 2y) = 18 + 18$$
$$5x - 2y + 4x + 2y = 36$$
$$9x = 36$$
6. **Solve for $x$:**
$$x = \frac{36}{9} = 4$$
7. **Substitute $x=4$ into the first original equation:**
$$-2(4) - y = -9$$
$$-8 - y = -9$$
8. **Solve for $y$:**
$$- y = -9 + 8$$
$$- y = -1$$
$$y = 1$$
9. **Final answer:**
$$\boxed{(x, y) = (4, 1)}$$
Linear Equations B48Ba5
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