A barrel of oil weighs 31.4 kilograms, and (1/5) of the oil weighs 26.4 kilograms. What is the weight of the barrel?
一桶油，连桶重31.4千克，用去(1/5)的油连桶重26.4千克，桶重是多少千克．
<gadget id="calculator">31.4 - 26.4</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>

<gadget id="calculator">31.4 - 25</gadget>
<output>6.4</output>

<result>6.4</result>