a) 96 km/h
The average speed can be calculated as the ratio between the total distance covered and the time taken:

where:
- the total distance is the total length of the path covered, regardless of the direction, so:
d = 22 km + 12 km + 14 km = 48 km
- total time:
t = 0.5 h
So, the average speed is

b) 14.4 km, at 33.7 degrees south of west
To find the displacement, we have to compute the net displacements along the two directions (north-south and east-west)
North-south direction (taking north as positive and south as negative):
(south)
East-west direction (taking east as positive):
(west)
So the net displacement is given by Pythagorean's theorem:

And the direction is given by

And the direction is south-west, so this is 33.7 degrees south of west
c) 28.8 km/h at 33.7 degrees south of west
The average velocity is the ratio between the net displacement and the time taken:

where we have:
displacement: d = 14.4 km
time taken: t = 0.5 h
So, the average velocity is

And the direction is the same as the displacement.