A pile of yellow sand, after using 4 tons, there is still (2/3) left, if 40% is used, how many tons are used.
一堆黄沙，用去4吨后还剩下(2/3)，如果用去40%，则用去多少吨．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 / (1/3)</gadget>
<output>12</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">12 * (2/5)</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>