a) Suppose, number of books that she needs to read = x
As 1 book costs for 5 points, It would be:
5x = 30
x = 6
So, she needs to read 6 books.
b) If she has read 7 books, her points would be:
7 * x
as x = 5 (point of 1 book)
7 * 5 = 35
So, she got 35 points.
Hope this helps!