I have 80 yuan, and I spent 38 yuan to buy a schoolbag, and I bought 3 more books with the remaining money. How much did you spend on average per book?
我有80元钱，买一个书包用了38元，剩下的钱又买了3本书．平均每本书用了多少元？
<gadget id="calculator">80 - 38</gadget>
<output>42</output>

<gadget id="calculator">42 / 3</gadget>
<output>14</output>

<result>14</result>