Teacher Wang took 700 yuan to sell books, bought 16 sets of books, and left 60 yuan. How much is the average book set?
王老师带700元去卖书，买了16套书，还剩60元．平均每套书多少钱？
<gadget id="calculator">700 - 60</gadget>
<output>640</output>

<gadget id="calculator">640 / 16</gadget>
<output>40</output>

<result>40</result>