The teacher buys several pens of a certain type for 216 yuan. If each pen is one yuan cheaper, then he can buy 3 more pens. How much is each pen?
老师用216元买一种钢笔若干支，如果每支钢笔便宜一元钱，那么他就可以多买3支，原来每支钢笔多少钱？
<result>9</result>