Mom bought 2.5 kilograms of green vegetables at the vegetable market, paid 5 yuan, got back 3 yuan, how much is it per kilogram of vegetables?
妈妈在菜场买了2.5千克青菜，付出5元，找回3元，每千克青菜多少元？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">2 / 2.5</gadget>
<output>0.8</output>

<result>0.8</result>