barrel of oil is used up (3/5), and the rest is 2 kg less than the used one. How many kilograms is this barrel of oil originally?
一桶油，用去(3/5)，剩下的比用去的少2千克．这桶油原来有多少千克？
<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">(3/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

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

<result>10</result>