It's winter, the little white rabbit only stored 180 carrots, and the little gray rabbit only stored 120 Chinese cabbages. In order to have radishes to eat in winter, the little gray rabbit exchanged a dozen stalks of Chinese cabbage for some carrots of the little white rabbit. At this time, the amount of food stored by them is equal. Then how many carrots can be exchanged for one Chinese cabbage.
过冬了，小白兔只储存了180只胡萝卜，小灰兔只储存了120棵大白菜．为了冬天里有萝卜吃，小灰兔用十几棵大白菜换了小白兔一些胡萝卜，这时他们储存的食物数量相等．则一棵大白菜可以换多少只胡萝卜．
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