A barrel of oil weighs 450 kilograms. After eating 3/4 of the oil, the remaining oil weighs 120 kilograms. How many kilograms does the barrel weigh?
一桶油连桶共重450千克，吃去油的(3/4)后，剩下的油连桶共重120千克，桶重多少千克？
<gadget id="calculator">450 - 120</gadget>
<output>330</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">330 / (3/4)</gadget>
<output>440</output>

<gadget id="calculator">450 - 440</gadget>
<output>10</output>

<result>10</result>