For a barrel of oil, 20 kilograms are poured out for the first time, and the remaining 30% is poured out for the second time. At this time, the remaining oil is the same as the total of the two pours. How many kilograms of oil are there in the barrel?
一桶油，第一次倒出20千克，第二次倒出余下的30%，这时，剩下的油和两次共倒出的同样多．原来桶里有油多少千克？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10) - (3/10)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 / (2/5)</gadget>
<output>50</output>

<gadget id="calculator">50 + 20</gadget>
<output>70</output>

<result>70</result>