A pile of river sand has 300 tons, use up (3/5), how many tons are left?
一堆河沙有300吨，用去(3/5)，还剩下多少吨？
<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">300 * (2/5)</gadget>
<output>120</output>

<result>120</result>