Zhenhai Yale School has 30 students going on a spring outing. If there are 2 students from the first group to the second group, and 5 students from the second group to the third group, the number of students in the three groups will be the same. How many people are there in the second group?
镇海雅乐学校有30个同学去春游，如果第一组到第二组2人，第二组到第三组5人，三个组的人数就一样多了．原来第二组有多少人．
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">10 - 2</gadget>
<output>8</output>

<gadget id="calculator">8 + 5</gadget>
<output>13</output>

<result>13</result>