Answer:
24 days (or more)
Explanation:
I assume you want to figure out how long it will take Tom to write the minimum amount of pages for his school report at that rate?
Since Tom writes 1/2 a page a day and he must write 12 or more pages, then it will take him 2 days to write one page, thus, 24 days to write 12 pages.
Therefore, Tom needs at least 24 days to write his school report.