Question 1189402
in 1 hour A can do 1/10 the job and B can do 1/12 the job.
At 10 am, A has been on the job 4 hours and has done 4/10. B has been on 1 hour and has done (1/12)
So the amount left to do is 1-(24/60)-(5/60) or 31/60
31/60/1/12=(31/60)*12=6.2 hours
10 am +6.2 hours is 4:12 pm
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4 hours of A (4/10)
7.2 hours of B (7.2/12)