A barrel of oil, the first time you eat this barrel of oil (1/4), the second time you eat this barrel of oil (1/5). Eat 2 kg more for the first time than the second time. How many kilograms does this barrel of oil weigh?
一桶油，第一次吃去这桶油的(1/4)，第二次吃去这桶油的(1/5)．第一次比第二次多吃2千克．这桶油共重多少千克？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">2 / (1/20)</gadget>
<output>40</output>

<result>40</result>