Xiao Ming read a story book, and after reading it for 4 days. This book is still (4/10) unfinished, how much of this book has he read?
小明看一本故事书，看了4天后．这本书还有(4/10)没看完，他看了这本书的几分之几？
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>