Xiao Ming reads a story book, reads (2/5) of the whole book on the first day, (1/5) of the whole book on the second day, reads the rest on the third day, and reads this book on the third day What fraction of?
小明看一本故事书，第一天看了全书的(2/5)，第二天看了全书的(1/5)，剩下的第三天看完，第三天看了这本书的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (2/5) - (1/5)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>