The elder brother gave 8 books of his own to the younger sister, so the younger sister still has 7 fewer books than the elder brother, and the elder brother has more books than the younger sister.
哥哥把自己的书送8本给妹妹，这样妹妹还是比哥哥少7本，哥哥原来比妹妹多多少本书．
<gadget id="calculator">8 + 8 + 7</gadget>
<output>23</output>

<result>23</result>