A barrel of oil is eaten (7/10), and another 15 kg is added. At this time, the oil in the barrel is exactly half of the oil in the barrel. How many kilograms does the barrel of oil weigh?
一桶油，吃了(7/10)，又添进去15千克，这时桶中的油正好是一桶油的一半，这桶油重多少千克？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/2) - (3/10)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">15 / (1/5)</gadget>
<output>75</output>

<result>75</result>