That is very much dependant on your specific situation.
For example, if the washer is on an exterior wall, or an interior bearing wall, the concrete there will be much thicker than the rest of the slab. Obviously, this makes it a much more involved and difficult process. And, of course, it depends on how far and to where you wish to move it, the piping arrangment under the slab, how everything is vented, etc. So many variables that would need to be looked at.