Xiao Pang went to the store to buy stationery. He brought a total of 100 yuan and bought 3 pens, each of which was 24 yuan. The remaining money can buy 7 exercise books, so how much is each exercise book?
小胖去商店买文具，他一共带了100元，买了3支钢笔，每支钢笔24元，剩下的钱正好可以买7本练习簿，那么每本练习簿多少元？
<gadget id="calculator">24 * 3</gadget>
<output>72</output>

<gadget id="calculator">100 - 72</gadget>
<output>28</output>

<gadget id="calculator">28 / 7</gadget>
<output>4</output>

<result>4</result>