The two fuel tanks hold a total of 82 kg of oil. If the oil in the first tank is injected into the second tank, 9 kg. At this time, the two fuel tanks have the same amount of oil. How many kilograms of oil was originally in the first fuel tank?
两个油箱共盛油82千克．如果把第一个油箱内的油注入到第二个油箱内9千克．这时两油箱的油就同样多．第一油箱内原来有油多少千克？
<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<gadget id="calculator">82 + 18</gadget>
<output>100</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<result>50</result>