i am confused on this question

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here they divide their answer by 4 at the end even though both units are in cm^3 so the ratio stays the same. i can not see why they do it?

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i also do not understand this question. i understand that they multiply at the end by 5 as there was a dilution factor of 5 but I do not see why they do not divide by 10 as the vinegar was in a 100 cm^3 volumetric flask .

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