Xiao Ming reads a 250-page story book, and has already read (2/5), how many pages are left unread?
小明看一本250页的故事书，已经看了(2/5)，还有多少页没有看？
<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>