Mom bought 3 kilograms of beef in the supermarket, paid 300 yuan, got back 60 yuan, how much is it per kilogram of beef?
妈妈在超市买了3千克牛肉，付出300元，找回60元，每千克牛肉多少钱？
<gadget id="calculator">300 - 60</gadget>
<output>240</output>

<gadget id="calculator">240 / 3</gadget>
<output>80</output>

<result>80</result>