Teacher Wang led the students to wipe the glass, and the students happened to be divided into 3 groups on average. If the teachers and students each wiped the same number of pieces, and a total of 111 pieces were wiped, how many pieces were wiped by each person on average?
王老师带领同学们擦玻璃，同学们恰好平均分成3组．如果师生每人擦的块数同样多，且一共擦了111块，那么平均每人擦了多少块？
<result>3</result>