How come my code doesn't work?

Question

#number of pages read
pages = int(input())
#rate of number of pages read per week
rate = 20
#number of pages in a book
book = 904
#number of weeks
weeks
if pages<book:
#finding how many weeks wiil it take to me finish
weeks = (book -pages)/rate
while weeks>8:
#increases the rate
rate =+1
break
print(weeks)
print(rate)

Answer 1

In addition to what @Ariela stated,
rate += 1
not
rate =+1
which will just set the value of rate to 1 as 1 and +1 mean the same thing.
Then you may also want to remove the break statement as the while loop will only run 1 time and exit as it is.

Answer 2

Assign weeks = 0