There are 231 students in the third and fourth grades of Lizhuang Primary School. There are 3 classes in the third grade, with an average of 45 students in each class. There are 2 classes in the fourth grade. How many students are in each class on average?
李庄小学三、四年级一共有231人，三年级有3个班，平均每班45人，四年级有2个班，平均每班多少人？
<gadget id="calculator">45 * 3</gadget>
<output>135</output>

<gadget id="calculator">231 - 135</gadget>
<output>96</output>

<gadget id="calculator">96 / 2</gadget>
<output>48</output>

<result>48</result>