There is a barrel of oil, (1/4) of the total amount is taken out for the first time, (2/5) of the total amount is taken out for the second time, and 75 kg more is taken out for the second time than the first time. How many kilograms is this barrel of oil originally?
有一桶油，第一次取出总量的(1/4)，第二次取出总量的(2/5)，第二次比第一次多取出75千克．这桶油原有多少千克？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">75 / (3/20)</gadget>
<output>500</output>

<result>500</result>