A (4/5) meter long wire, (1/4) of the wire is used for the first time, how many meters are left at this time?
一根(4/5)米长的电线，第一次用去这跟电线的(1/4)，这时还剩多少米？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(4/5) * (3/4)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>