A piece of wire is used up (3/4), how much of the wire is left.
一段铁丝用去它的(3/4)，还剩这段铁丝的多少．
<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>

<result>1/4 = around 0.25</result>