How can I calculate the rotation value of a model to look at a position?

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14

I need the Y rotation to rotate the head of tank animated not fast in one step.

I need the Y value to use it in this way:

public void head_to(float deg) {

    Quaternion qua = new Quaternion().fromAngleAxis(FastMath.DEG_TO_RAD * deg, new Vector3f(0, 1, 0));
    Tween rot = SpatialTweens.rotate(head, head.getLocalRotation(), qua, 1f);
    anim.add(Tweens.smoothStep(rot));

    turning_sound.playInstance();
}