Both Xiao Ming and Xiao Hong have 30 books, after Xiao Ming gives Xiao Hong 10 books, how many more books does Xiao Hong have than Xiao Ming?
小明和小红都有30本书，小明送给小红10本后，小红比小明多多少本．
<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">40 - 20</gadget>
<output>20</output>

<result>20</result>