Mom bought 3.5 kilograms of eggs at the farmer's market, paid the conductor 40 yuan, and got 6.4 yuan back to calculate how much it is per kilogram of eggs.
妈妈到农贸市场买了3.5千克鸡蛋，付给售票员40元，找回6.4元算一算，每千克鸡蛋多少元．
<gadget id="calculator">40 - 6.4</gadget>
<output>33.6</output>

<gadget id="calculator">33.6 / 3.5</gadget>
<output>9.6</output>

<result>9.6</result>