Answer: 18 days
Step-by-step explanation:
We can divide the number of pages by the rate of pages read per day to find the number of days it would take to finish the book.
[tex]\displaystyle \frac{216\text{ pages}}{12\frac{\text{pages}}{\text{day}} } =216\div12 \text{ days}=18\text{ days}[/tex]
