Velocity,time,acceleration question

[drinkingstraw]

A blue car moving at constant speed of 10m/s passes a polic car that is at rest. The police car accelerates from rest at 4m/s^2 for 3.0 seconds and then maintains a constant speed. The blue car maintains constant speed for the entire 12 seconds. When does the police car pass the blue car?

Calculations:
Blue Car:
Vi= 10 m/s
Vf = 10 m/s
deltaT = 12 s
deltaD = 120 m
acceleration = 0

Police Car:
Vi = 0m/s
acceleration = 4m/s^2 (for the first 3 seconds)
deltaD (for first three seconds) = 18 m
Vf = 12 m/s

So when the deltaD of the blue car = the deltaD of the police car, the police car is at the same distance as the blue car.

How would I go about doing this?

 

[CompuChip]

Note how this problem is similar to this question.
Probably if you solve the other one, you will be able to do this one yourself.