Each week, rosario drives to an ice skating rink that is 120 miles away. the round-trip takes 2.75 hours. if he averages 55 miles per hour on his way to the rink, which equation can be used to find x, the number of miles per hour he averages on his way home?

Distance = rate * time

trip there,  120 = 55 *t
                   t = 2 and 2/11 hours

trip back,  120 = r * (2.75 - 2.181818181)  round trip time - time to get there
                 120 = r * .568181818181818
                  r = 211.2 miles per hour

thinking maybe you did not copy the problem accurately...thats pretty fast. 

First find how much time it took to make the trip to the skating rink. The skating rink is 120 miles away and his average speed is 55 miles per hour.