During the National Day, Teacher Li took some students to visit the zoo. Tickets are 8.50 yuan per person, and a total of 127.5 yuan was spent on buying tickets, and 67.5 yuan should be prepared to buy back tickets. Please ask questions according to the conditions.
国庆期间，李老师带部分同学去动物园参观．门票每人8.50元，买门票共花了127.5元，还要准备67.5元买回去的车票．根据条件请你提出问题．
<gadget id="calculator">127.5 / 8.5</gadget>
<output>15</output>

<result>15</result>