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.