There is half a barrel of oil in an oil barrel, use up 40% first, and then pour 10 liters of oil into it, then the oil in the barrel is the same as before. How many liters of oil can this barrel hold?
一只油桶里装有半桶油，先用去40%，再倒入10升油，这时桶里的油和原来一样多．这个桶能装多少升油？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">10 / (2/5)</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<result>50</result>