It's just speed, distance, time
Speed = D/T
Distance = SxT
Time = D/S
Therefore Speed (or velocity) = D/T = 55/1.4 = 39 MPH rounded up - FOR JOURNEY 1
Velocity = D/T = 55/2 = 22.5 MPH - FOR JOURNEY 2
To work out his average speed (velocity) you add these together and divide by 2
Average = (39+22.5)/2
Answer = 30.75MPH or 31MPH rounded up
Hope this helps :) + If I'm wrong I'm sorry lol