Aunt Wang sold eggs. She sold 12 kilograms in the morning and 18 kilograms in the afternoon, which was 27.6 yuan more in the afternoon than in the morning. How much is the average egg sold per kilogram?
王大妈卖鸡蛋，上午卖出了12千克，下午卖出了18千克，下午比上午多卖了27.6元．平均每千克鸡蛋卖多少元．
<gadget id="calculator">18 - 12</gadget>
<output>6</output>

<gadget id="calculator">27.6 / 6</gadget>
<output>4.6</output>

<result>4.6</result>