A story book has 250 pages, and I have read (2/5) of the whole book, how many pages are left?
一本故事书250页，已经看了全书的(2/5)，还剩多少页没有看？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">250 * (3/5)</gadget>
<output>150</output>

<result>150</result>