Total work done by both machines in a minute = 30 + 20 = 50 copies
Total number of copies required = 2000
Time = 2000/50 = 40 mins
One copy machine can make 30 copies a minute, and a second copy machine makes 20 copies a minute. If the two copiers work together, how long would it take them to make 2,000 copies?
a. 20 minutes
b. 40 minutes
c. 45 minutes
d. 50 minutes
e. 55 minutes