$\"\"$

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Since $\"\"$ is an altitude of $\"\"$ .

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So, $\"\"$ is a right angle.

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$\"\"$ are complementary angles.

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$\"\"$ (Complemenrary angles theorem)

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$\"\"$ (Substitute $\"\"$ , $\"\"$ )

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$\"\"$ (Add: $\"\"$ )

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

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$\"\"$ (Divide each side by 10) $\"\"$

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Use $\"\"$ to determine the measure of $\"\"$ .

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$\"\"$ (Given)

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Simplify) $\"\"$

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The value of x is 7 and $\"\"$ .