The third grade students donated books, Class 3 1 donated 42 books, Class 3 2 donated 58 books, Class 3 3 donated 47 books, how many books each class donated on average.
三年级同学捐书，三1班捐了42本，三2班捐了58本，三3班捐了47本，平均每班捐多少本．
<gadget id="calculator">42 + 58 + 47</gadget>
<output>147</output>

<gadget id="calculator">147 / 3</gadget>
<output>49</output>

<result>49</result>