某禽养场备有520只鸡可吃15天的精饲料,这些鸡吃了6天后,卖掉了160只鸡,余下的饲料还可吃几天?

共有520只鸡,可吃15天,那么久共有520×15=7800的精饲料
吃了六天,那么就吃了520×6=3120的精饲料
那么就剩7800-3120=4680的精饲料
然后卖掉160只鸡,就剩了520-160=360只鸡
余下的饲料可吃的天数就等于余下的饲料除以余下的鸡
也就是4680÷360=13天
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520*（15-6）÷（520-160）=13

还可以吃13天！