There is a barrel of oil, after pouring out 60%, there are 30 liters left in the barrel, how many liters of oil are there in the barrel?
有一桶油，倒出60%后，桶里还剩30升，这桶油原来有多少升？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">30 / (2/5)</gadget>
<output>75</output>

<result>75</result>