数学题：一根电线，第一次剪下2/5（五分之二），又接上18米，这样比原来长20%（百分之二十）。这根铁丝原来长几米？（18米就是全长的五分之二与全长的百分之二十的米数之和）

数学题解答：18÷（2/5　+　20%）＝30（米）

答：这根铁丝原来长30米。

推荐阅读：
Content Creation Startup, Presto Media Sees Incredible Success W　 These Nightmare Stories Will Remind You How Important It Is To B　 Your Blog as an ROI Generator　 How Blogging Has Become An Important Tool In Schools　 5 Of The World’s Greatest Marketing Blog Posts And What We Can L　 3 Ways to Create a Killer Blog　 How the Bitcoin Market is Recovering from the Bitfinex Hack　 Singaporean Blogger Amos Yee Pleads Guilty to More Charges; Goin　 Why Aren’t Your Visitors Sharing Your Post on Social Media　 Bloggers: Jumpstart Cash Flow With These Tips