Wang Li read a 100-page storybook, read the whole book (1/4) on the first day, and read the whole book (2/5) on the second day. How many pages are left unread?
王丽看一本书100页的故事书，第一天看了全书的(1/4)，第二天看了全书的(2/5)．还剩下多少页没有看？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) + (2/5)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1 - (13/20)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">100 * (7/20)</gadget>
<output>35</output>

<result>35</result>