Each cutting machine cuts 105 parts every 3 minutes. There are 5 cutting machines because one cutting machine is shut down.
In order to determine how many parts the 5 cutting machines cut in 4 1/2 hours, multiply the factor 105/3 by 5 (number of cutting machines) by the factor 4 1/2 but in minutes:
4 1/2 = 4.5 hours = 4.5 (60 min) = 270 min
then,
(5)(105 parts/ 3min)(270 min) = 47,250
Hence, in 4 1/2 hours the rest of the cutting machines cut 47,250 parts
