A road is 72 kilometers long, and it has been traveled (4/9), how many kilometers are left to go.
一条公路长72千米，已经走了(4/9)，还剩多少千米没走．
<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">72 * (5/9)</gadget>
<output>40</output>

<result>40</result>