Teacher Wang typed 42 characters per minute, and it took 12 minutes to type a paper. If Mr. Wang finishes typing this thesis in 9 minutes, how many words per minute will he type on average?
王老师每分钟打42个字，打一篇论文需要12分钟．如果王老师9分钟打完这篇论文稿，平均每分钟打多少个字？
<result>120</result>