The fifth grade students of Jiangsu Road Elementary School spontaneously set up two "Learning from Lei Feng" groups, A and B. The number of people in group A is three times that of group B, and 10 people are transferred from group A to group B. At this time, the number of the two groups is equal. How many people are in the group?
江苏路小学五年级的同学自发成立甲、乙两个"学雷锋"小组，甲组人数是乙组人数的3倍，从甲组调10人到乙组，这时两组人数相等，原来乙组有多少人？
<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>