For a barrel of oil, (2/5) kilograms are poured out for the first time, (3/8) kilograms are poured out for the second time, and (1/4) of this barrel of oil is poured out twice, how many kilograms is this barrel of oil?
一桶油，第一次倒出(2/5)千克，第二次倒出(3/8)千克，两次正好倒出这桶油的(1/4)，这桶油有多少千克？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(2/5) + (3/8)</gadget>
<output>31/40 = around 0.775</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(31/40) / (1/4)</gadget>
<output>31/10 = around 3.1</output>

<result>31/10 = around 3.1</result>