A barrel of oil weighs 40 kilograms. After pouring out (4/5) of the oil, the barrel still weighs 12 kilograms. How many kilograms of oil are there in the barrel?
一桶油，连桶重40千克，倒出油的(4/5)后，连桶还重12千克，桶里原来有油多少千克？
<gadget id="calculator">40 - 12</gadget>
<output>28</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">28 / (4/5)</gadget>
<output>35</output>

<result>35</result>