There is a barrel of oil that takes out (1/4) of the total amount for the first time, and 5 kg more than the first time for the second time, and the result is 20 kg left. How many kilograms is this barrel of oil originally?
有一桶油第一次取出总数的(1/4)，第二次比第一次多取5千克，结果还剩20千克．这桶油原来有多少千克？
<gadget id="calculator">20 + 5</gadget>
<output>25</output>

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

<gadget id="calculator">1 - (1/4) - (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">25 / (1/2)</gadget>
<output>50</output>

<result>50</result>