I need help with a few problems

Question

a freight train traveling with a velocity of 18.0 m/s to the south begins braking as it approaces the train yard.  The train's acceleration whole braking is -0.332.  What is the train's speed after 23 seconds?

Answer 1

speed = a*t + v₀

 

where:

a is the acceleration = -0.332 m/s²

v₀ is the train's initial speed = 18.0 m/s

 

speed = (-0.332)*t + 18.0

 

at t = 23 seconds,

 

speed = (-0.332)*(23) + 18.0 = _____?