SOLUTION: Two printing presses are available to print the daily college newspaper. If only one press is used, it takes the older press twice as long to print an edition as it takes the newer

It is the same as to have THREE identical printers, where 2 of them "replace" and "play the role" of one newer printer.


So, if the three printers do the entire job in 3 hours, it means that each of the three, working alone, will do the job in 9 hours.


Answer.  9 hours for old printer and  = 4.5 hours for newer printer each working alone.

Let x be the rate of work of the slower printer, measured in "job-per-hour".


Then the rate of work of the faster printer is 2x "jobs-per-hour", according to the condition.


Also, according to the condition,


x + 2x =   of the job per hour,    or


3x = .


It implies  x = ,   which means that the slower printer makes    of the job per hour.


In turn, it means that the slower printer will make the entire job in 9 hours, working alone.


And you get the same answer.