For a barrel of diesel oil, take out (2/5) of the total number for the first time, and take out the rest (3/4) for the second time, leaving 12 kilograms. How many kilograms is this barrel of oil originally?
一桶柴油，第一次取出总数的(2/5)，第二取出余下的(3/4)，还剩12千克，这桶油原来有多少千克？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/5) * (3/4)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (2/5) - (9/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">12 / (3/20)</gadget>
<output>80</output>

<result>80</result>