It really depends on how complex the problem is as to how many steps it will take.  Eventually you will simplify the problem down to something like this:

3x-9 = 3x+4  so -9 = 4  ???

If you get that result that means that there is no possible solution since no value you substitute for x will make the statement true.

You may also get something that simplifies down to this:

3x + 4 = 3x +4  so 4 = 4

If you get this result it means you have infinite solutions since any value you substitute for x will make the statement true.

Hope this helps for the problem you are working on