GWD-26-37 总是求助 ~

Q37:

In a meeting of 3 representatives from each of 6 different companies, each person shook hands with every person not from his or her own company.  If the representatives did not shake hands with people from their own company, how many handshakes took place?

A.     45

B.      135

C.      144

D.     270

E.      288

答案是B

一点思路没有 求助~

可以用排除法。先将所有可能的握手组合算出，C（18，2）=153，再减去同一个公司的握手C（3，2），因为6个公司，共6*3=18种握手是公司内部滴。153-18=135

非常感谢~