There are three students, one of them is 3 years older than the other, the product of their ages is 1620, what is the sum of the ages of these three students?
有三个学生，他们的年龄一个比一个大3岁，他们三个人年龄数的乘积是1620，这三个学生年龄的和是多少岁．
<gadget id="calculator">9 + 12 + 15</gadget>
<output>36</output>

<result>36</result>