There are two piles of river sand, the first pile is 60% heavier than the second pile, then how much is the second pile lighter than the first pile
有两堆河沙，第一堆比第二堆重60%，那么，第二堆比第一堆轻多少
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 + (3/5)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(3/5) / (8/5)</gadget>
<output>3/8 = around 0.375</output>

<result>3/8 = around 0.375</result>