ShmoopTube

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Put this in your calculator and shmoop it...

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If a + b = 12, b + c = 17, and a + c = 9, what is the value of a + b + c?

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And here are the potential answers...

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If we push our way through the annoying crowd of variables...

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...we'll find that what this question is actually asking

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is just for us to sum a, b, and c.

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What if... we add up all three of the equations that are given to us?

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In that case, we get a + b + b + c + a + c equals 12 + 17 + 9.

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And if we combine all like terms...we get 2a + 2b + 2c equals 38.

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Next, we can distribute the 2 to make the equation 2 times the quantity a + b + c... equals 38.

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Divide both sides by 2, and our equation looks like this: a + b + c = 19.

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Answer B.

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