In the fourth and fifth grades, 220 trees will be planted. There are 3 classes in the fourth grade, and 28 trees are planted in each class, and the rest are distributed to the 4 classes in the fifth grade. How many trees are planted in each class on average?
四、五年级要栽220棵树．四年级有3个班，每班栽28棵，剩下的分给五年级4个班栽，平均每班栽多少棵？
<gadget id="calculator">28 * 3</gadget>
<output>84</output>

<gadget id="calculator">220 - 84</gadget>
<output>136</output>

<gadget id="calculator">136 / 4</gadget>
<output>34</output>

<result>34</result>