Teacher Zhang paid 100 yuan to buy 7 teacups, and the salesperson got back 16 yuan. How much is an average teacup?
张老师付出100元买7个茶杯，营业员找回16元．平均每个茶杯多少元．
<gadget id="calculator">100 - 16</gadget>
<output>84</output>

<gadget id="calculator">84 / 7</gadget>
<output>12</output>

<result>12</result>