A marketing firm determined that, of 200 households surveyed, 80 used neither Brand A nor Brand B soap, 60 used only Brand A soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 200 households surveyed used both brands of soap?
想问问大家and for every household that used both brands of soap, 3 used only Brand B soap.这句话是怎么理解的
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发表于 2017-8-4 21:47:15
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