There is a barrel of oil, (2/5) of the total weight is taken out for the first time, and 4 kg is taken out for the second time, and (1/3) of the total weight remains in the barrel. How many kilograms of the original oil are in the barrel?
有一桶油，第一次取出总重量的(2/5)，第二次取出4千克，桶里还剩总重量的(1/3)，桶里原有油多少千克？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (2/5) - (1/3)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">4 / (4/15)</gadget>
<output>15</output>

<result>15</result>