There are 4 groups in Class 1 of Grade 3 in our school, and each group has 9 people. They planted 144 trees on Arbor Day. How many trees are planted per person on average?
我校三年级1班有4个小组，每个小组有9人，他们在植树节共植树144棵．平均每人植树多少棵？
<gadget id="calculator">144 / 4 / 9</gadget>
<output>4</output>

<result>4</result>