Xiao Lin's teacher bought back 143 exercise books and distributed them to Xiao Lin and his 12 classmates on average. How many copies per person on average?
小林的老师买回143本练习簿，平均分给小林和他的12个同学．平均每人分多少本？
<gadget id="calculator">1 + 12</gadget>
<output>13</output>

<gadget id="calculator">143 / 13</gadget>
<output>11</output>

<result>11</result>