1 watermelon is 12 yuan, and 3 pineapples are 24 yuan. How much is a watermelon more expensive than a pineapple? What is the correct column
1个西瓜12元，3个菠萝24元，一个西瓜比一个菠萝贵多少元？列式正确的是多少
<gadget id="calculator">24 / 3</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>