Teacher Sun wants to use 80 yuan to buy some stationery as a prize for the grade sports meeting. He first bought 10 photo albums for 47.5 yuan, and plans to use the remaining money to buy some pens, each pen is 2.5 yuan, how many pens can Mr. Sun buy?
孙老师要用80元买一些文具作为年级运动会的奖品．他先花47.5元买了10本相册，并准备用剩下的钱买一些钢笔，每枝钢笔2.5元，孙老师还可以买几枝钢笔？
<gadget id="calculator">80 - 47.5</gadget>
<output>32.5</output>

<gadget id="calculator">32.5 / 2.5</gadget>
<output>13</output>

<result>13</result>