Basic transmission concepts (Semi Urgent)

[CamNuge]

Hello,
    I am a Telephone techincian with SBC.  I have a test that I am taking for advancement tomorrow.  I have studied all of the topics given to me and prepared myself as well as I can.  However, I have been unable to find an answer to one of the questions on a sample test that I took, and I haven't been able to find any material on the subject that answers it for me.

   The question is in Macromedia Flash form so I cannot directly link the image with my level of knowledge.  However, the root of the question can be addressed without seeing the diagram. 

   The diagram shows a basic telephone loop, represented in the simplest form as a single line from the Central Office (CO) to a series of phone jacks broken only by a repeater (basic amplifier diagram of a triangle is used).  The loop is labled at the CO with 0dB.  It then goes on to give a gain of -2.4dB across the first section of conductors, a gain of 8.1dB across the repeater, another gain (loss) across the second section of conductors.  The question finishes by asking for the dB at the output phone jacks A, B, etc..
 
  The numbers are irrelevant though, as my problem is not with my skills in math (I hope    ).  My issue is that I am not sure how to add gain across multiple components given no current or power or voltages.  Can the dB simply be added? If so, then I messed up the math somewhere.  All I was told was I missed that particular question, not what the correct answer was.  Gotta love the Scantron eh?     

   Any help with this would be greatly appreciated, and the sooner the reply the better as I take the test in about 18 hrs.


    Thanks very much,
                  Cameron

[Staigen]

Hi there Cameron, welcome to this forum, its nice to have you here

Can the dB simply be added?

As far as i know, yes, db is just added. And db is always related to something.

//Staigen