Question 211753
Let  x  = angle,  y= supplement,,or y=180-x
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y= 2x +9,,,,,,,given
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180-x = 2x +9
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-3x = - 171
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x=57,,,,,,,,y=180-57 = 123
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check, 57 +123=180,,,ok
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123 = 2(57) +9 = 123,,,ok
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