I'm reading a book named "Programming Game AI by Example". Here's a method to help an autonomous character to slow down when it's getting closer and closer to its target:

Vector2D SteeringBehavior::Arrive(Vector2D TargetPos, Deceleration deceleration)
{
    Vector2D ToTarget = TargetPos - m_pVehicle->Pos();

    //calculate the distance to the target
    double dist = ToTarget.Length();

    if (dist > 0)
    {
        //because Deceleration is enumerated as an int, this value is required
        //to provide fine tweaking of the deceleration..
        const double DecelerationTweaker = 0.3;

        //calculate the speed required to reach the target given the desired
        //deceleration
        double speed =  dist / ((double)deceleration * DecelerationTweaker);     

        //make sure the velocity does not exceed the max
        speed = min(speed, m_pVehicle->MaxSpeed());

        //from here proceed just like Seek except we don't need to normalize 
        //the ToTarget vector because we have already gone to the trouble
        //of calculating its length: dist. 
        Vector2D DesiredVelocity =  ToTarget * speed / dist;

        return (DesiredVelocity - m_pVehicle->Velocity());
    }

    return Vector2D(0,0);
}

For this line:

//calculate the speed required to reach the target given the desired
//deceleration
double speed =  dist / ((double)deceleration * DecelerationTweaker);

I just don't understand how can it get a speed by dividing a distance by an acceleration (deceleration)? Did I misunderstand anything?