There is a barrel of oil, 2/5 is used for the first time, 20 kg is used for the second time, and there is still 34 kg of oil in the barrel. How many kilograms is this barrel of oil?
有一桶油，第一次用去(2/5)，第二次用去20千克，桶里还有油34千克．这桶油有多少千克？
<gadget id="calculator">20 + 34</gadget>
<output>54</output>

<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">54 / (3/5)</gadget>
<output>90</output>

<result>90</result>