A class of students went on a spring outing. It was just right for 20 people to take one car when they went there, and it was just right for 15 people to take one car when they came back. What is the minimum number of people in this class?
一个班的同学去春游，去时20个人坐一个车刚好，回来时15人坐一个车也刚好．问这个班最少有多少人？
<gadget id="calculator">2 * 2 * 3 * 5</gadget>
<output>60</output>

<result>60</result>