解,设总页数为C,小红未读为A,则小红已读为C-A,
小明未读为B,则小明已读为C-B
根据题意,得:C-A = (2/5)B C-B = (3/7)A
因为C相同,所以 (2/5)B+A = (3/7)A+B
A(1-3/7) = B(1-2/5)
A(4/7) = B(3/5)
A/B = (3/5)/(4/7) = 21/20
所以,小红未读与小明未读的页数比是21:20.
解,设总页数为C,小红未读为A,则小红已读为C-A,
小明未读为B,则小明已读为C-B
根据题意,得:C-A = (2/5)B C-B = (3/7)A
因为C相同,所以 (2/5)B+A = (3/7)A+B
A(1-3/7) = B(1-2/5)
A(4/7) = B(3/5)
A/B = (3/5)/(4/7) = 21/20
所以,小红未读与小明未读的页数比是21:20.