Rachel had to complete 12 pages of math homework. If she had to complete 12 more pages of math homework than reading homework How many pages did she have to complete in all?
1. Rachel had to complete 12 pages of math homework.
2. If she had to complete 12 more pages of math homework than reading homework...
3. How many pages did she have to complete in all?

So we're looking for the total number of pages of homework she had to complete. We know that 12 of those pages were math homework, and we're told that she had to complete 12 more pages of math homework than reading homework. So that means she had to complete 24 pages of math homework in total. We don't know how many pages of reading homework she had to complete, but we can figure it out by subtracting 12 from 24. That means she had to complete 12 pages of reading homework. So the total number of pages of homework she had to complete was 24 + 12, or 36 pages.