Dealing with Velocity and acceleration. What do I do next? =P

[CowzRule101]

Homework Statement

David is driving a steady 21.0 m/s when he passes Tina, who is sitting in her car at rest. Tina begins to accelerate at a steady 2.70 m/s^2 at the instant when David passes.

David:
V= 21m/s

Tina:
V_i= 0 m/s
V_f= ?
acc= 2.7 m/s^2

How far does Tina drive before passing David?
What is her speed as she passes him?

Homework Equations

D_f= D_i + V_i + t_f + (1/2)at_f^2
V_f^2= V_i^2 + 2a(D_f - D_i)
V_f= V_i +at

The Attempt at a Solution

Well, I really don't have an attempt because I have no clue what to do. Any suggestions

 

[Kurdt]

At the point Tina catches David their distances should be the same. You can set the two equations of motion equal and then solve for time. Once you have time you can solve for the other things.