Teacher Li planted 91 trees with more than ten students, and each person planted the same number of trees. How many students participated in planting trees?
李老师和十多名同学一起种树，一共种了91棵，每人种树的棵树相等．有多少名同学参加种树？
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<result>12</result>