$\"\"$

The equations are

$\"\"$ Equation (1)

$\"\"$ Equation (2) $\"\"$

Eliminate the variable s by addicting the equation (1) and (2).

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Divide each side by 3.

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

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

Apply subtraction property of equality: if a = b, then $\"\"$ .

Subtract 3 from each side.

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Divide each side by negative one. \ \

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The solution is $\"\"$ .