Solve for a
a=21-b
Solve for b
b=21-a
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a+b=\frac{1}{2}\times 42
Multiply both sides by 42.
a+b=21
Multiply \frac{1}{2} and 42 to get 21.
a=21-b
Subtract b from both sides.
a+b=\frac{1}{2}\times 42
Multiply both sides by 42.
a+b=21
Multiply \frac{1}{2} and 42 to get 21.
b=21-a
Subtract a from both sides.
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