Nancy has bought 10 different Christmas presents.In how many ways can she
a.divide present into 5 group of 2?
b.give all present to 2friend such that each of them receives at least 3 presents?
收錄日期: 2021-04-23 20:43:46
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110608000051KK01213