$\"\"$

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The equations are

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$\"\"$ Equation (1)

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$\"\"$ Equation (2)

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Solve the first equation for z in terms of w.

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Apply addition property of equality; if a = b, then $\"\"$ .

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$\"\"$ (Add w to each side)

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Apply commutative property of addition: $\"\"$ .

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$\"\"$

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

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$\"\"$ (Apply subtractive identity property: $\"\"$ )

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Multiply each side by negative one.

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$\"\"$

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$\"\"$

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$\"\"$

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Substitute $\"\"$ in Equation (2).

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$\"\"$

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$\"\"$

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Apply commutative property of addition: $\"\"$ .

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$\"\"$

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Distribute terms using Distributive property: $\"\"$ .

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$\"\"$

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$\"\"$

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Subtract 10 from each side.

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$\"\"$

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$\"\"$

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$\"\"$

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Multiply each side by negative one.

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$\"\"$

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$\"\"$

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Substitute $\"\"$ in equation in equation $\"\"$ .

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$\"\"$

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Product of two same sings is positive.

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$\"\"$

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$\"\"$

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$\"\"$

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The solution is $\"\"$ .