A cylinder of oil weighs 10 kilograms, pour (1/5) away, if (1/5) kilograms are poured out again, how many kilograms are left.
一筒油重10千克，倒去(1/5)，如果再倒去(1/5)千克，还剩多少千克．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 * (1/5)</gadget>
<output>2</output>

<gadget id="calculator">10 - 2 - (1/5)</gadget>
<output>39/5 = around 7.8</output>

<result>39/5 = around 7.8</result>