Xiaohong has collected 30 stamps, and Xiaofang has collected 24 stamps. How can she exchange them so that they both have the same number of stamps?
小红收集了30张邮票，小芳收集了24张邮票，她怎样交换，两个人的邮票张数一样多？
<gadget id="calculator">30 + 24</gadget>
<output>54</output>

<gadget id="calculator">54 / 2</gadget>
<output>27</output>

<gadget id="calculator">30 - 27</gadget>
<output>3</output>

<result>3</result>