Mr. Zhang bought 12 pens at the stationery store, paid 50 yuan, and got back 21.2 yuan. How much is each pen?
张老师在文具店买了12支笔，付出50元，找回21.2元，每支笔多少钱？
<gadget id="calculator">50 - 21.2</gadget>
<output>28.8</output>

<gadget id="calculator">28.8 / 12</gadget>
<output>2.4</output>

<result>2.4</result>