There is a wire that is many meters long, 25 meters have been used, and the full length (4/9) is left.
有一条长多少米的电线，用去25米，还剩下全长的(4/9)．
<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">25 / (5/9)</gadget>
<output>45</output>

<result>45</result>