Modify distance with var?

Hello guys, well I have been dealing with this all day and I can not get it working…
I wrote a script to orbit the camera around my character, everything works as expected.
I have not defined the min and max zoom allowed on the player but I will use mathf.Clamp… To do that First: I am going to need a var on the inspector that modifies the “distance”.
What ive got now is:

var dst: float;

function Update(){ dst =
Vector3.Distance
(target.position,transform.position);
}

But this var only reads the distance (cant modify it), how can I create one that can be modified via inspector, I know it is something simple but I have not found the answer.

Thanks for your time.

If I understand what you are looking for, you wish to get a position (P) for a camera (C) that is a fixed distance (D) from a game object (G). The way I would do this would be to determine the vector that would be G.position - C.position … call this V1. Then I would normalize this vector so it has unit length … call this V2. Next I would multiply V2 * D which would give me a vector from G to P. And thus to calculate P, the answer would be G.position + V2.