To determine how many nights it will take Niall to finish the book, we first need to calculate how many pages he has left to read.
Total pages in the book: 520 pages
Pages read so far: 100 pages
Pages left to read = Total pages - Pages read
Pages left to read = 520 - 100 = 420 pages
If Niall plans to read 60 pages per night, we can find the number of nights it will take him by dividing the pages left by the number of pages he reads each night:
Number of nights = Pages left to read / Pages read per night
Number of nights = 420 / 60 = 7 nights
So, it will take him 7 nights to finish the book.
The correct response is 7.