有三堆棋子，每堆棋子数一样多。都只有黑白两种颜色，第一堆中的黑子，和第二堆中的白子一样多。第三堆中的黑子占全部黑子的2/5，求三堆棋子中，白子占全部棋子的几分之几？

（这个题目有点绕人，如果一时想不明白，还是先画线段图表示吧！）

推荐阅读：
Starting a Blog? 5 Topics People Care About in 2017　 6 Strategies To Grow Your Facebook Page　 5 Sure Shot Content Marketing Trends to Follow　 7 Ways for Your Underdog Blog to Beat the Competition　 Darkstore Aims to be Less Invasive Alternative to Tech Giants ac　 5 Free Blogging Apps You Need On Your IPhone Right Now　 The Exact Amount that You Must Spend on a Great Blog Is…　 How to Make Videos Search Engines Love　 5 Thoughts For Investing In Your Freelancing Career In 2017　 How YouTube Can Work in Tandem With Your Blog