Question 980732
Printer A: 1 project/12 minutes=1/12 project/min
Printer B: 1 project/42 minutes=1/42 project/min
Together: 1/12 project/min + 1/42 project/min=(7/84+2/84)project/min = 9/84_project/min
To print 1 project at 9/84 project/min:
(1_ project)/(9/84_project/min)=9.33minutes