Opposite sides of a parallelogram are equal to each other
therefore make the opposite sides equal to each other in an equation.
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We'll have 2 equations:
3y - 6 = 21 and 5x + 2 = 17
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Solve the first equation
3y - 6 = 21
Add 6 to both sides
3y = 27
Divide both sides by 3
y = 9
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Solve the second equation
5x + 2 = 17
Subtract 2 from both sides
5x = 15
Divide both sides by 5
x = 3
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![\boxed {x = 3,~y =9}](https://img.qammunity.org/2019/formulas/mathematics/high-school/ryadgsahlo7f526hq0pe7982er6r42fpjt.png)
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