遇到这样绕的题，怎么做喃？高手出招提点

丫丫兔

·Of the 800 students at a certain college, 250 students live on campus and are more than 20 years old. How many of the 800 students live on campus and are 20 years old or less?
    

(1)   640 students at the college are more than 20 years old.

(2)   60 students at the college are 20 years old or less and live off campus.

答案是C.

怎么做吖，头都昏了。。。

bluell66

这题似乎应该画表格，分别列明住校、不住校、20岁以上和20岁及以下

住校且20及以下的应该是100人吧？

丫丫兔

恩，我算出来了。THX！