Solve for a
a=12
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72-3a-3a=0
Subtract 3a from both sides.
72-6a=0
Combine -3a and -3a to get -6a.
-6a=-72
Subtract 72 from both sides. Anything subtracted from zero gives its negation.
a=\frac{-72}{-6}
Divide both sides by -6.
a=12
Divide -72 by -6 to get 12.
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