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has 2 oxygens for every carbon.
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will contribute one of each for every molecule. You then have to have an even multiple of
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molecules to not end up with an odd number of oxygens.
So if you take
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, you should end up with 2 carbons on the RHS.
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then has 4 oxygens. 2 of them are already accounted for, so you just need one
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to balance out the reaction.
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