a motorcyclist sees a branch in the road and hits the brakes, slowing down at - 6.42 m/s. if it takes him 2.85 us to stop, what was his starting velocity

Acceleration: - 6.42 m/second squared. [ a ]

Final Velocity: 0 m/s [ v ]

Time: 2.85 s. [ t ]

Initial / starting velocity:? [ u ]

v = u + a x t

By substituting above values,

0 = u + - 6.42 x 2.85

0 = u + (-18.297)

0 = u - 18.297

u = 18.297

Starting velocity = 18.297 m/s