Xiaogang reads a 140-page story book. He reads (2/7) of this book on the first day and (3/7) of this book on the second day. How many pages are left?
小刚读一本140页的故事书，第一天读了这本书的(2/7)，第二天读了这本书的(3/7)，还剩多少页没有读？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (2/7) - (3/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">140 * (2/7)</gadget>
<output>40</output>

<result>40</result>