The fifth grade students went to the pedestrian street to participate in the activity of "Learning Economics from Little Fleas". There were 12 students from Class 51, and each person sold 5 books on average. There were 15 people in class 5 and 2, and a total of 102 books were sold. How many books does each person sell on average in the two classes of the fifth grade?
五年级同学到步行街参加"小跳蚤学经济"活动，五1班有12人参加，平均每人卖图书5本．五2班有15人参加，共卖图书102本．五年级两个班平均每人卖图书多少本？
<gadget id="calculator">12 * 5</gadget>
<output>60</output>

<gadget id="calculator">60 + 102</gadget>
<output>162</output>

<gadget id="calculator">12 + 15</gadget>
<output>27</output>

<gadget id="calculator">162 / 27</gadget>
<output>6</output>

<result>6</result>