Solve for a
a=3
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8a+7=10+21
Combine 12a and -4a to get 8a.
8a+7=31
Add 10 and 21 to get 31.
8a=31-7
Subtract 7 from both sides.
8a=24
Subtract 7 from 31 to get 24.
a=\frac{24}{8}
Divide both sides by 8.
a=3
Divide 24 by 8 to get 3.
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