There are 10 kilograms in a barrel of oil, (4/5) is used for the first time, and (4/5) is used for the second time, how many kilograms are left.
一桶油有10千克，第一次用去(4/5)，第二次又用去(4/5)千克，还剩多少千克．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">10 * (4/5)</gadget>
<output>8</output>

<gadget id="calculator">10 - 8 - (4/5)</gadget>
<output>6/5 = around 1.2</output>

<result>6/5 = around 1.2</result>