分析：已讀的頁數(shù)是未讀的頁數(shù)的75%=3/4,則已讀的頁數(shù)占總頁數(shù)的3/（4+3）=3/7.如果再讀96頁,那么已讀的頁數(shù)是未讀的頁數(shù)的6倍,則已讀的頁數(shù)是總頁數(shù)的
6/（6+1）=6/7.即96頁相當(dāng)于總頁數(shù)的6/7-3/7=3/7,即可求出總頁數(shù).
75%=3/4
3÷（4+3）=3/7
6÷（6+1）=6/7
96÷（6/7-3/7）=224頁
答：這本書共有224頁.