Question 201706
A + B = 180,,,,def  supplementary
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B= (70-x),,,,given
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A +(70-x) =180
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A + (70-x) = 180
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A = 180 -70 +x 
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A= 110 +x
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check,  x=10, (70-x) =60,,,A=120,,,answer,,,110+10=120,,,,ok