The elder brother has 25 cards, and the younger brother has 13 cards. How many cards does the elder brother give to the younger brother, so that they can have the same number.
哥哥有卡片25张，弟弟有13张，哥哥要给弟弟多少张，他们才能一样多．
<gadget id="calculator">25 + 13</gadget>
<output>38</output>

<gadget id="calculator">38 / 2</gadget>
<output>19</output>

<gadget id="calculator">25 - 19</gadget>
<output>6</output>

<result>6</result>