Aunt Li in the cafeteria bought 5.5 kilograms of beans at the market, gave it to the salesperson for 20 yuan, and got back 4.6 yuan. How much is it per kilogram of beans?
食堂李阿姨在市场买了5.5千克豆角，交给售货员20元钱，找回4.6元，每千克豆角多少钱？
<gadget id="calculator">20 - 4.6</gadget>
<output>15.4</output>

<gadget id="calculator">15.4 / 5.5</gadget>
<output>2.8</output>

<result>2.8</result>