Final answer:
The formula used to calculate gph is gph = mpg / mph.
Step-by-step explanation:
The formula used to calculate gallons per hour (gph) is gph = mpg / mph. This formula is derived from the unit conversion between miles per gallon (mpg) and miles per hour (mph). To calculate gph, you divide the mpg by the mph, as gph represents the number of gallons used in one hour of driving at a certain speed.
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