A barrel of oil weighs 60 kilograms in total, and after using (3/5) of the oil, the total weight of the barrels is 30 kilograms. What is the net weight of this barrel of oil?
一桶油连桶共重60千克，用去油的(3/5)后，连桶共重30千克．这桶油净重多少千克？
<gadget id="calculator">60 - 30</gadget>
<output>30</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 / (3/5)</gadget>
<output>50</output>

<result>50</result>