A 225-page story book, after reading how many pages, there is still the whole book (2/5).
一本225页的故事书，读了多少页后，还剩全书的(2/5)．
<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">225 * (3/5)</gadget>
<output>135</output>

<result>135</result>