A barrel of oil is used for the first time (2/5), the second time is 2 kg more than the first time, and there are 3 kg left in the barrel. How many kilograms is this barrel of oil originally?
一桶油，第一次用去(2/5)，第二次比第一次多2千克，桶里还剩下3千克．这桶油原来有多少千克？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5 / (1/5)</gadget>
<output>25</output>

<result>25</result>