I read a book with a smile, I read (1/6) of the whole book on the first day, and (2/5) of the whole book on the second day. How much of the book is left?
笑笑看一本书，第一天看了全书的(1/6)，第二天看了全书的(2/5)．还剩下全书的几分之几？
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/6) - (2/5)</gadget>
<output>13/30 = around 0.433333</output>

<result>13/30 = around 0.433333</result>