see the attached figure to better understand the problem
Step 1
Find the number of pages printed on an Apricot printer
we know that
The speed of an Apricot printer is 8ppm
so
in 4.5 min
Carlos print
4.5*8=36 pages
step 2
Find the time it takes Carlos to print the same amount of documents on a sure fire printer printer
we know that
The speed on a sure fire printer is 12ppm
so
Divide the total of pages by the speed of the printer
36/12=3 minutes
therefore
the answer is
3 minutes