There is a barrel of oil weighing 80 kilograms. Take out the full barrel (1/4) for the first time, and take out the remaining 40% for the second time. How many kilograms of oil are left in the barrel?
有一桶油重80千克，第一次取出全桶的(1/4)，第二次取出余下的40%，桶里还剩油多少千克？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/4) * (2/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/4) - (3/10)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">80 * (9/20)</gadget>
<output>36</output>

<result>36</result>