An Acara traveled from Meridell to Brightvale, 50 miles away, with his pet Pawkeet. When he arrived in Brightvale, he let the pawkeet fly free while he traveled back to Meridell, at a speed of 10 miles per hour. The pawkeet, who flies at 25 miles per hour, arrived at Meridell and promptly turned around until he got to the Acara. Once he got to the Acara, he turned around and returned to Meridell. He continued to fly back and forth between the Acara and Meridell until the Acara reached Meridell.
Unless I'm missing something it's quite simple. The Acara travels 50 miles at 10 m.p.h., taking 5 hours. The pawkeet flies back and forth for the same 5 hours at 25 m.p.h., so travels 125 miles.