$\"\"$ $\"\"$

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The equations are

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$\"\"$ (equation 1)

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$\"\"$ (equation 2) $\"\"$

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Since $\"\"$

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Rewrite the second equation for x.

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$\"\"$

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$\"\"$ (Subtract 2y from each side)

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$\"\"$ (Additive inverse property: $\"\"$ )

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$\"\"$ (Additive identity property: $\"\"$ ) $\"\"$

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Now Substitute $\"\"$ for x in either equation to find the value of y.

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$\"\"$ (equation 1)

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$\"\"$ (replace $\"\"$ )

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$\"\"$ (Distributive property: $\"\"$ )

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$\"\"$ (Multiply: $\"\"$ ) $\"\"$

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$\"\"$ (Subtract: $\"\"$ )

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$\"\"$ (Subtract 20 from each side)

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$\"\"$ (Commutative property: $\"\"$ )

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$\"\"$ (Additive inverse property: $\"\"$ )

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$\"\"$ (Additive identity property: $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ ) $\"\"$

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$\"\"$ (Divide each side by 70)

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$\"\"$ (Cancel common terms)

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$\"\"$ (Multiply each side by negative one)

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$\"\"$ (Product of two same signs is positive) $\"\"$

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Now $\"\"$

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$\"\"$ (replace y by 1)

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$\"\"$ (Multiplicative identity property: $\"\"$ )

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$\"\"$ (Subtract: $\"\"$ )

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

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The solution is $\"\"$ .