To solve the equation \(-3x - 9 = -21\), we can follow these steps:
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Start with the original equation: \[ -3x - 9 = -21 \]
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Add 9 to both sides to isolate the term involving \(x\): \[ -3x - 9 + 9 = -21 + 9 \] This simplifies to: \[ -3x = -12 \]
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Now, divide both sides by \(-3\) to solve for \(x\): \[ x = \frac{-12}{-3} \] This simplifies to: \[ x = 4 \]
Thus, the solution to the equation \(-3x - 9 = -21\) is \(x = 4\).
You can also verify the solution by plugging \(x = 4\) back into the original equation: \[ -3(4) - 9 = -12 - 9 = -21 \] This confirms that the solution is correct.
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