数学题：一份稿件，甲、乙两人合打5小时完成，甲的工作效率相当于乙的80％，若这稿件由乙完成，需要几小时？

数学题解答：设稿件为1，这便是工作总量，只需求出乙的工效，便可以算出乙单独完成所需的时间。

甲、乙两人合打5小时完成，说明两人的工效和是1/5。

设乙工效为X，则有：

80%X　+　X　=　1/5

X＝1/9

乙的工效是1/9，所以乙单独完成所需的时间是：1　÷　1/9　＝　9　（天）

推荐阅读：
Big O Simply Explained　 How to Rotate a Matrix (Clockwise and Anti-clockwise) in place?　 The Odds Are Ever in Your Favor: The Numbers Game of Earning Cli　 Beyond Infographics: Alternative Visual Content Strategies That 　 7 Keys to Business Success for Young Digital Marketers　 4 Ways to Deepen Engagement with Your Blog Audience　 Attract Tech Talent To Your Small Business With This Expert Advi　 3 Steps To A Better Classifieds Website　 Jailed Saudi Blogger’s Children Plead For His Release　 Chatbots and the Changing Art of Blogging