A book has 100 pages, I have read (3/4), how many pages are left unread.
一本书有100页，已看了(3/4)，还剩下多少页没看．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">100 * (1/4)</gadget>
<output>25</output>

<result>25</result>