Final answer:
To calculate the deadline for Mr. Chou to mail the form, count backward 25 days from November 3, which lands on October 9 as the last day he can mail the form.
Step-by-step explanation:
The question involves calculating a deadline based on a specific number of days before a given date, which is a mathematics problem dealing with calendar dates. Mr. Chou can mail the form no later than 25 days before November 3. To find the last day he can mail the form, we need to count backward 25 days from November 3.
- Start with November 3.
- Counting back one day would be November 2 (1 day).
- Continue counting back until you reach 25 days before November 3.
If we count back 25 days from November 3, we find that the last day he can post the form is October 9.