A barrel of oil, take out 35% of the barrel of oil for the first time, and take out 15 kg for the second time, which is exactly half of the oil in the barrel. How many kilograms does the barrel of oil weigh in total?
一桶油，第一次取出这桶油的35%，第二次再取15千克就刚好剩下这桶油的一半，这桶油一共重多少千克？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">(1/2) - (7/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">15 / (3/20)</gadget>
<output>100</output>

<result>100</result>