There are two barrels of oil. (3/4) of the first barrel of oil is equal to the weight of the second barrel of oil. The total weight of the two barrels of oil is 12 kg. How much is the weight of the first barrel of oil?
有两桶油，第一桶油的(3/4)与第二桶油重量相等，两桶油共重12千克，第一桶油重多少千克？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 + (3/4)</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">12 / (7/4)</gadget>
<output>48/7 = around 6.857143</output>

<result>48/7 = around 6.857143</result>