Xiaohua bought 4 kilograms of apples with 20 yuan, and got back 4 yuan, how much is a kilogram of apples
小华用20元钱买了4千克苹果，找回4元，每千克苹果是多少元
<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<result>4</result>