Question 12296
First of all, you need to put all of the information from the question into equations (I have added these to your question).

You know that {{{3W = A}}}, so change the W in the second equation to {{{(1/3)A}}}.  Also, since you know from the third equation that {{{B = (1/2)A}}}, you can plug (1/2)A in for B.  Now you have {{{(1/3)A + A = (1/2)A + 30,000}}}.

To solve this equation, combine like terms to simplify.  Now you have {{{(4/3)A = (1/2)A + 30,000}}}.  Move (1/2)A to the other side of the equation by subtracting:  {{{(5/6)A = 30,000}}}.  Solve the equation by dividing:  {{{A = 36,000}}}.