Speed can never be negative because it does not depend in which direction the car moves whereas, velocity will change if a car turns from due North to East.
Quantities which can be described only by their magnitudes are called scalars and those which are described by both, magnitude and direction are vectors
My educated guess : 21.2 deg
The answer is C. in sort of a way. You can't technically see black matter. However, it is holding the galaxies together.
Answer:
V = V0 + a t
V = 75 - 9.8 * 3 = 45.6 m/s
