40% of a barrel of oil is poured out for the first time, 15 kg is poured out for the second time, and the ratio of the third poured out to the original barrel of oil is 1:4, and there are still 20 kg left. How many kilograms is this barrel of oil?
一桶油第一次倒出40%，第二次倒出15千克，第三次倒出的与原桶油的比是1：4，这时还剩20千克．这桶油有多少千克？
<gadget id="calculator">15 + 20</gadget>
<output>35</output>

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

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

<gadget id="calculator">1 - (2/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">35 / (7/20)</gadget>
<output>100</output>

<result>100</result>