For a barrel of oil, (2/5) is used for the first time, and (1/3) is used for the second time, and the first time is 2 kg more than the second time. How many kilograms is this barrel of oil?
一桶油，第一次用去(2/5)，第二次用去(1/3)，第一次比第二次多2千克．这桶油多少千克？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(2/5) - (1/3)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">2 / (1/15)</gadget>
<output>30</output>

<result>30</result>