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

2 answers

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?