WE know that (distance) = Speed * time and Speed = distance/time & time = distance/speed
Let AB = 60 mi. & the speed is 55 mi/h , then the spent to reach the rink is
t= 60/55 = 1.09 h Since the total time is 2.75 h & he spent 1.09h to go to the rink, so the time spent on his way back is 2.75-1.09 = 1.659 h So his speed on his way back is 60/1.659 =36.16 mi/h