SOLUTION: The average of a set of 12 numbers, which include 34, is A. If 34 is removed from the set and 38 is included to the set, what is the average of the new set of number in terms of A

I won't do your problem for you.  Instead I'll do one EXACTLY like it
so you can do yours EXACTLY the same way.

I'll do this one instead:

Suppose the set of 14 numbers is {28,B,C,D,E,F,G,H,I,J,K,L,M,N}

Since the average = A,



So we multiply both sides by 14:



We substract 28 from both sides



We add 45 to both sides





We divide both sides by 14:



Answer:  

Now do yours the same way.

Edwin