book has 200 pages, Xiao Ming read it (3/5) on the first day, how many pages are left.
一本书有200页，小明第一天看了它的(3/5)，还剩多少页没有看．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">200 * (2/5)</gadget>
<output>80</output>

<result>80</result>