Let x represent the time to clean one dispensers.
Clean 6 dispensers: 35 minutes
Clean 1 dispenser: x minutes
Steps:
Use cross multiply
1*35=6*x
35=6x
Divided 6 to each side
35/6=6x/6
x=5.8 minutes or 5 minutes 48 seconds. As a result, it has taken 5 minutes and 48 seconds to clean 1 dispenser. Hope it help!