Answer:
4.8 minutes
Step-by-step explanation:
Using the given hint, working together, the amount of floor mopped in 1 minute is ...
1/8 + 1/12 = 3/24 +2/24 = 5/24 . . . . jobs/minute
The reciprocal of that is the rate in terms of minutes per job. Thus the entire job takes 24/5 = 4.8 minutes.