Take it one step at a time.
-- Remember that 'speed' means (distance) divided by (time),
and the direction doesn't matter.
-- Remember that 'velocity' means the speed and the direction.
First car:
360 meters east in 15 sec.
Speed = 360/15 = 24 meters per second
Velocity = 24 meters per second east
Second car:
120 meters west in 5 seconds
Speed = 120/5 = 24 meters per second
Velocity = 24 meters per second west
-- Their speeds (24 and 24) are equal.
-- Their velocities are equal magnitude but opposite (24 east / 24 west).
