Dad reads a novel, read 240 pages, and there are (4/7) left to read, how many pages are left to read?
爸爸看一本小说，看了240页，还剩(4/7)没有看，还剩多少页没有看？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">240 / (3/7)</gadget>
<output>560</output>

<gadget id="calculator">560 - 240</gadget>
<output>320</output>

<result>320</result>