A barrel of oil weighs 26 kilograms, and after pouring out (1/5) the weight of the barrel is 21 kilograms. How many kilograms is this barrel of oil?
一桶油连桶重26千克，倒出(1/5)后连桶重21千克．这桶油原来多少千克？
<gadget id="calculator">26 - 21</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<result>25</result>