I don't see how I have enough information to answer this question

If a car is traveling westward with a constant velocity of 20 m/s what is the net external velocity

well the net force is obivuosley greater than friction sense it's moving

allowing it to move 20 m/s

f=ma

i don't know the mass so I don't know what to do here?

here's another one that i have no idea how to do

If a car is accelerating downhill under a net force of 3674 N what force must the brakes exert to cuase the car to have a constant velocity?

To determine the net external velocity, we need sufficient information about the other external forces acting on the car. In this case, if we assume there are no other external forces acting on the car, then the net external velocity would be equal to the car's velocity.

However, please note that we generally use the term "net external force" rather than "net external velocity" to describe the combined effect of all external forces acting on an object.

If you are looking for the net external force acting on the car, then we would need additional information about other forces like friction, air resistance, or any other forces acting on the car.