A book has 300 pages. I read the whole book (1/3) in the first week, and read the remaining pages (4/5) in the second week. How many pages are left?
一本书300页，第一星期看了全书的(1/3)，第二星期看的页数是余下的(4/5)，还剩多少页没看？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">300 * (1/3)</gadget>
<output>100</output>

<gadget id="calculator">300 - 100</gadget>
<output>200</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">200 * (1/5)</gadget>
<output>40</output>

<result>40</result>