A story book has 180 pages, Xiaohong has already read it (4/9), how many pages are left?
一本故事书180页，小红已经看了(4/9)，还剩多少页没有看？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (4/9)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">180 * (5/9)</gadget>
<output>100</output>

<result>100</result>