There are three classes in Grade 5 of Sunshine Huimin No. 2 Primary School. The average number of students in classes A and B is 51, the average number of students in classes B and C is 56, and the average number of students in classes A and C is 55. How many students are there on average in each of these three classes?
阳光回民二小五年级有三个班，甲乙两班平均人数有51人，乙丙两班平均人数是56人，甲丙两班平均人数是55人，这三个班平均每班多少人？
<gadget id="calculator">51 + 56 + 55</gadget>
<output>162</output>

<gadget id="calculator">162 / 2</gadget>
<output>81</output>

<gadget id="calculator">81 / 3</gadget>
<output>27</output>

<result>27</result>