Solve for x
x=15
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80-4x-20=0
Add 40 and 40 to get 80.
60-4x=0
Subtract 20 from 80 to get 60.
-4x=-60
Subtract 60 from both sides. Anything subtracted from zero gives its negation.
x=\frac{-60}{-4}
Divide both sides by -4.
x=15
Divide -60 by -4 to get 15.
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