Question 281855
filling the facet is 1 job

Cold facuet fills in 10 minutes

So it does 1/10 of the job in 1 minute

Hot facuet fills in 12 minutes

so it does 1/12 of the job in 1 minute

1/10  +1/12 of the job they do together in 1 minute  = 22/120 

22/120 job in 1 minute

1 job they will do in 120/22 minutes

= 5.45 minutes