The school carried out the "Learning from Lei Feng" activity. All members of the school's art group spontaneously organized some handicrafts for the elderly in the nursing home. The students in the art group first did it for one day, and then added 15 students to do it with them for two days. Just completed the task. Assuming that each student has the same work efficiency, and it takes 60 days for a student to complete alone, please calculate how many people there are in the art group?
学校开展"学雷锋"活动，校艺术小组全体成员自发组织做一些工艺品送给敬老院的老人，开始艺术小组的同学们先做一天，随后又增加了15位同学和他们一起又做了两天，恰好完成任务．假设每位同学的工作效率相同，且一位同学单独完成需要60天，请你算出艺术小组有多少人？
<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/60) * 2 * 15</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/60) * 3</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/2) / (1/20)</gadget>
<output>10</output>

<result>10</result>