ARGPILOT, Farmer 1 was incorrect when he wrote
Distance to PNR = (Endurance in hours x gs out x gs home)/gs out + gs home
as this simplifies to endurance x gs home + gs home - which is incorrect.
The solution you asked for is 4 hours, 49 minutes and a fraction over 42 seconds (assuming an infinitely quick turn back) to arrive back with dry tanks.
Seat1APlease's advice was spot on, including the correct formula, leaving you the (simple) task of 'gathering terms'. Capt. Slow's version was also correct, with the correct answer.
It seems somewhat odd that you should thank the one contributor who 'told you wrong', yet you managed to miss the two correct solutions which were given to you.
PM