barrel of peanut oil is half used and poured into 12 kilograms. At this time, the oil in the barrel is the original oil (4/5). How many kilograms of peanut oil were there in the barrel?
一桶花生油用去一半后又倒进12千克，这时桶内的油是原来油的(4/5)．桶里原来有花生油多少千克？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(4/5) - (1/2)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">12 / (3/10)</gadget>
<output>40</output>

<result>40</result>