Aunt Wang bought 16.5 kilograms of rice with 50 yuan, and the price of rice per kilogram is 2.40 yuan. How much should I get back?
王大妈用50元钱买16.5千克大米，每千克大米价格2.40元，应找回多少元？
<gadget id="calculator">16.5 * 2.4</gadget>
<output>39.6</output>

<gadget id="calculator">50 - 39.6</gadget>
<output>10.4</output>

<result>10.4</result>