Question

What is the answer to 8x-5674=[c+-4577] What is c

Answer 1

It's not completely clear what you want.   Your  8x-5674=[c+-4577]  has two variables:  x and c.  You can solve this for x or you could solve it for c, but not for both.  Also, your "+-" should be written as "-"  (unless you meant "plus OR minus 4577)."

So there are several different approaches, depending upon what you meant!
If you mean this:    8x - 5674=[c - 4577] and want to solve for c,  do the following:
1.  Remove the unnecessary brackets  [  ]
2.  Add 4577 to both sides the resulting equation.  The result will be the expression for c that you wanted.  Note that you must combine -5674 and 4577.