Xiaolan bought 2 pens and 3 exercise books, and obviously bought 15 of the same exercise books, and the two spent the same amount of money. The price of 1 pen is equal to the price of how many exercise books.
小兰买了2枝钢笔和3本练习本，明明买了15本同样的练习本，两人用去的钱一样多．1枝钢笔的价钱等于多少本练习本的价钱．
<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<result>6</result>