To solve the equation \( 2(x - 3) + 21 = -3 \), we can break down the solution into clear steps.
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Distribute: We will distribute the \(2\) in the equation.
\[ 2(x - 3) = 2x - 6 \]
So, the equation becomes:
\[ 2x - 6 + 21 = -3 \]
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Combine like terms: Next, we can combine the constants \(-6\) and \(21\).
\[ -6 + 21 = 15 \]
So, the equation now is:
\[ 2x + 15 = -3 \]
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Use the subtraction property of equality: We will subtract \(15\) from both sides of the equation to isolate the term with \(x\).
\[ 2x + 15 - 15 = -3 - 15 \]
Which simplifies to:
\[ 2x = -18 \]
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Use the division property of equality: Now, we divide by \(2\) to solve for \(x\).
\[ \frac{2x}{2} = \frac{-18}{2} \]
This gives us:
\[ x = -9 \]
So, the final solution is
\[ \boxed{-9} \]