A (4/5) meter steel pipe, after cutting off (1/5), how much is left
一根(4/5)米的钢管，截去(1/5)后，还剩多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>