After printing the books for 8 days, if 1 more machine was added, the number of days in which the remaining work would be completed is 8 days.
Based on the information provided above, the total number of days which the 2 printing machines can complete the printing in 20 days can be calculated as follows;
Total number of days (2 printing machines) = 2 × 20
Total number of days (2 printing machines) = 40 days.
For the total number of days in printing the books for 8 days, we have the following:
Total work days = 2 × 8
Total work days = 16 days.
Next, we would determine the number of days that are remaining as follows;
Remaining days = Total number of days (2 printing machines) - Total work days
Remaining days = 40 - 16
Remaining days = 24 days.
Since 1 more printing machine will be added, the total number of machine becomes 3 printing machines. Therefore, we would divide the remaining days by 3 as follows;
Number of days to complete the work = 24/3
Number of days to complete the work = 8 days.