Xiaoyue and Dongdong went to the bookstore to buy books together. They bought 15 math books and 22 Chinese books in total. Among them, Xiaoyue bought 4 times more math books than Dongdong, and Dongdong bought 3 times more Chinese books than Xiaoyue. 2 copies. May I ask: How many more books did Dongdong buy than Xiaoyue?
小悦和冬冬一起去书店买书，一共买了15本数学书和22本语文书，其中小悦买的数学书是冬冬的4倍，冬冬买的语文书比小悦的3倍多2本．请问：冬冬买的书比小悦多多少本？
<gadget id="calculator">22 - 2</gadget>
<output>20</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<result>5</result>