A hose fills a hot tub at a rate of 3.45 gallons per minute. How many hours will it take to fill a 280 ​-gallon hot​ tub?

For this case we must use the following definition:
 Q = V / t
 Where,
 Q: flow
 V: volume
 t: time
 Clearing the time we have:
 t = V / Q
 Substituting the values:
 t = (280) / (3.45)
 t = 81.16 minutes
 In hours we have:
 t = (81.16) * (1/60)
 t = 1.35 hours
 Answer:
 it will take to fill to 280 -gallon hot tub about:
 t = 1.35 hours