Machine A working alone can complete a job in 3 1/2 hours. Machine B working alone can do the same job in 4 2/3 hours. How long will it take both machines working together at their respective constant rates to complete the job?
A. 1 hour 10 min
B. 2 hr
C. 4 hr 5 min
D. 7 hr
E. 8 hr 10 min
A. 1 hour 10 min
B. 2 hr
C. 4 hr 5 min
D. 7 hr
E. 8 hr 10 min
