Please help with DECELERATION problem

[somnium]

With motion problems, what formula do i use for deceleration of a particle if I am given v and a, and need to find distance?

 

[Päällikkö]

For constant acceleration:
x = x₀ + v₀t + (1/2)at²

 

[somnium]

So, to find braking distance for each train in this problem:

Two trains, one traveling at 72 km/h and the other at 133 km/h, are headed toward one another along a straight, level track. When they are 860 m apart, each engineer sees the other's train and applies the brakes. The brakes decelerate each train at the rate of 1.0 m/s2.

would I use negative acceleration?

 

[somnium]

and what do i do about the fact that time isn't specified in the question?

 

[Valhalla]

http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/1DKin/U1L6a.html

look on the equations on this page...find any that might work?

 

[somnium]

vf^2=vi^2+2ad

you are awesome

 

[somnium]

I have another question: How do I go about this one:

A drowsy cat spots a flowerpot that sails first up and then down past an open window. The pot was in view for a total of 0.35 s, and the top-to-bottom height of the window is 2.10 m. How high above the window top did the flowerpot go?

I tried v=-gT+Vo and y=-.5gT^2+VoT
but I think I'm missing something in the way the question is phrased.
It gives total time, but no other numbers to plug in...