Kinetics of Particles : Newton's Second Law

Determine the maximum theoretical speed that may be achieved over a distance of 50 m by a car starting from rest, knowing that the coefficient of static friction is 0.80 between the tires and the pavement. Assume four-wheel drive. In answering this problem, how can you use the coefficient of friction without mass?

Kinetics of Particles: Work and Energy

See attached. I have an answer but need all the steps involved. Numbers in FIG. P13.26 from top to bottom are: 0.3m, 0.6m, and 1.5m. Letters in FIG. P13.26 from top to bottom are: C, A, and B.