The third grade students donated books to the "Hand in Hand" friends. Class 1 donated 184 books, Class 2 and Class 3 both donated 168 books, Class 4 donated 172 books, Class 5 had 1 more book than Class 4. How many books are donated by each class on average?
三年级同学给"手拉手"小伙伴捐图书．1班捐了184本，2班和3班都捐了168本，4班捐172本，5班比4班多1本．平均每个班捐了图书多少本？
<gadget id="calculator">172 + 1</gadget>
<output>173</output>

<gadget id="calculator">184 + 168 + 168 + 172 + 173</gadget>
<output>865</output>

<gadget id="calculator">865 / 5</gadget>
<output>173</output>

<result>173</result>