To get the number of pages she read for one day you'll have:
210pages/7days = 30pages/day
therefore Maria reads 30pages each day

I salute maria, i can't take reading 1 page a day xD
Anyway, why people always ask very simple math question here that can easily be answered if they just try to comphrehend. This one was very easy it's just simple division -_-
remember that we have different levels of comprehension skills. and the ones that were asking this kind of questions are the little children at grade school. (-_-)!
To get the answer you should first know how many books does she read each day so the first thing you should do is to divide 210 which is the number of pages by 7 which is the days so then you got know 30.

Therefore Maria read 30 pages per day. And in 7 days she would read a total number of 210 pages