For a rope, if 2.4 meters are subtracted, 40% of the total length remains; if you want to keep 3/5 of the total length, how many meters should be subtracted.
一根绳子，若减去2.4米，还余下全长的40%；若想余下全长的(3/5)，应减去多少米．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">2.4 / (3/5)</gadget>
<output>4</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 * (2/5)</gadget>
<output>8/5 = around 1.6</output>

<result>8/5 = around 1.6</result>