An oil barrel, after filling (2/5) barrels of peanut oil, the total weight of the barrel is 8.5 kg. After the barrel is full, the total weight of the barrel is 16 kg. How much does this barrel of oil weigh?
一个油桶，装进(2/5)桶花生油后，连桶共重8.5千克，把桶装满后，连桶共重16千克，这桶油重多少千克？
<gadget id="calculator">16 - 8.5</gadget>
<output>7.5</output>

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

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">7.5 / (3/5)</gadget>
<output>12.5</output>

<result>12.5</result>