getting a sum from two scripts

Alright, I had no idea on how to word this into a short "topic" question, not even really sure on the terminology... but here's my dilemma: I have three .js scripts, one for car, one for racer, and one for player.

In the car script ("KartScript.js") I have the following:

 public var krtSpdLand : float;

which is a float designated in the unity engine's inspector.

In the racer script ("RacerScript.js") I have the following:

 racSpdLand = 3;

My problem is that I cannot seem to get the player script ("PlayerScript.js") to do the math that I want it to... which is:

 spdLand = RacerScript.racSpdLand + KartScript.krtSpdLand;

I am trying to get the sum of the 2 floats to become the float value for the Player Script's "spdLand."

I have searched and I cannot seem to find anything that even resembles this.

Thanks ahead of time for your help.