Final answer:
To calculate how long it will take the student to read the rest of the book, determine the number of pages left and the student's reading speed.
Step-by-step explanation:
To calculate how long it will take the student to read the rest of the book, we need to know how many pages are left and the student's reading speed. Let's assume the book has a total of 100 pages. If the student has already read 2/5 (2/5 x 100 = 40 pages), then there are 100 - 40 = 60 pages left. If the student reads at a speed of 10 pages per day, it will take them 60 / 10 = 6 days to read the rest of the book.