There are (2/5) liters of oil in barrel A, and if (1/4) liters are poured out of barrel B, there will be as much oil as barrel A. How many liters of oil are there in barrel A and barrel B?
甲桶有油(2/5)升，乙桶如果倒出(1/4)升，就和甲桶一样多，原来甲、乙两桶共有油多少升．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) + (1/4) + (2/5)</gadget>
<output>21/20 = around 1.05</output>

<result>21/20 = around 1.05</result>