There are 150 people in two classes, A and B, and 60 people in class B. How many people are transferred from class A to class B, and the number of people in the two classes is exactly equal?
甲乙两个班共150人，乙班有60人，从甲班调多少人到乙班，两个班的人数正好相等？
<gadget id="calculator">150 - 60 - 60</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<result>15</result>