The teacher prepared the 10-day summer camp living expenses for 12 students, and as a result, 3 more students joined the summer camp. If the daily fee per person remains the same, how many days can the teacher prepare these fees?
老师为12名学生准备好了10天夏令营生活的费用，结果又增加了3名学生参加夏令营．如果每人每天的费用不变，老师准备的这些费用可维持几天？
<gadget id="calculator">12 * 10</gadget>
<output>120</output>

<gadget id="calculator">1 / 120</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">1 / (1/120) / 15</gadget>
<output>8</output>

<result>8</result>