A barrel of oil with barrels weighs 120 kg, and after (3/7) of the oil is used, the weight of the barrels is 75 kg. How much does the barrel of oil weigh in kilograms?
一桶油连桶重120千克，用去(3/7)油后，连桶重75千克．这桶油原来重多少千克．
<gadget id="calculator">120 - 75</gadget>
<output>45</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">45 / (3/7)</gadget>
<output>105</output>

<result>105</result>