$\"\"$

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The system of equations are $\"\"$ and $\"\"$ .

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$\"\"$ ------------(1)

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$\"\"$ ---------(2)

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The second equation is already solved for c.

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The value of $\"\"$ substitute in the first equation, $\"\"$ .

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$\"\"$

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Apply distributive property: $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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Add 4 to each side.

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$\"\"$

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$\"\"$

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Subtract 3d from each side.

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$\"\"$

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$\"\"$

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$\"\"$

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The value of $\"\"$ substitute in the either equation to find c.

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$\"\"$ (second equation)

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$\"\"$

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$\"\"$

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The solution is $\"\"$ . $\"\"$

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The solution is $\"\"$ .