A stated rotorcraft reserve calculation

A fictional VFR rotorcraft planning exercise supplies a flight time of 2 hours and a constant normal-cruise consumption of 12 gallons per hour. It asks for trip fuel plus the twenty-minute normal-cruise amount identified in 91.151(b), with taxi and all other allowances expressly excluded from the arithmetic. One learner adds 20 gallons because the reserve duration is 20 minutes. Another calculates the requested amount but describes it as a universal safe arrival target. The task asks for the numerical result and the distinction between the stated legal planning element and a complete operational decision. No actual aircraft, usable capacity, changing wind, weather or route is supplied. A complete answer keeps the duration conversion explicit and does not infer that minimum fuel alone guarantees a suitable flight.