求助

Of the 60 animals on a certain farm,  [?] are either pigs or cows.  How many of the animals are cows?

(1)  The farm has more than twice as many cows as it has pigs.

(2)  The farm has more than 12 pigs.

 答案是Ｃ

一共40只猪，或者牛，这一点没有问题。条件1说牛比猪的两倍还多，条件2说，猪多于12只，那么结合一下条件1，2和已知条件，就得出猪是13只，牛是27只。