The fountain in the pond behind kevins school has a pump that recirculates 60 gallons of water every 1/5 of an hour.express this rate as a unit rate in gallons per hour?

The necessary information's are already given in the question. Based on those information's the answer to the question can be easily determined.
Amount of water recirculated by the pump in 1/5 of an hour = 60 gallons
we already know
1/5 of an hour = (1/5) * 60 minutes
                         = 12 minutes
Then
Amount of water recirculated by
the pump in 60 minutes = (60/12) * 60 gallons
                                         = 5 * 60 gallons
                                         = 300 gallons
So the amount of water recirculated by the pump per hour is 300 gallons.    

The frequency of the guitar string vibrates back and forth 88 times in 1 minute = 1.5 Hz

Step-by-step explanation:

A hertz is used to measure one cycle (complete wave) of a vibration.

The number of cycles per second is the frequency, measured in hertz.

A guitar string vibrates back and forth 88 times in 1 minute

The vibrations in 1 second = = 1.466 Hz ≈1.5 Hz

The frequency of the guitar string vibrates back and forth 88 times in 1 minute = 1.5 Hz