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Quantity[19.25, "Kilometers"] + Quantity[13, "Miles"]

Quantity[40.171472, Kilometers]

Quantity[20, "Feet"] / Quantity[2.3, "Seconds"] + Quantity[9, "Meters" / "Seconds"]

Quantity[38.22321122903116, Feet/Seconds]

N[Quantity[175, "Pounds"] / Quantity[100, "Kilograms"]]

0.7937866475

Quantity[24, "Miles" / "Gallons"] * Quantity[16.2, "Gallons" / IndependentUnit["tank"]] * Quantity[1 / 8, IndependentUnit["tank"]]

Quantity[48.599999999999994, Miles/Gallons*Gallons/IndependentUnit["tank"]*IndependentUnit["tank"]]