Hello! I would love to help!
Let's start by decreasing 32 pages to 28. How many pages does it take to get from 28 to 32? Let's subtract to find out!
32-28=4
Okay, now we know 28 pages is 4 less than 32.
Now, what percentage did it decrease by? Let's find out by dividing!
4/32=0.125
Let's make that decimal into a percentage by multiplying it by 100.
0.125*100=12.5
So, we now know the answer is...
decreased by 12.5%
Hope this helped! Comment if you have questions!