prev_room_width = ???
prev_room_height = ???
with(all)
{
    x_multiplier = controller.prev_room_width/x;
    y_multiplier = controller.prev_room_height/y;
    x = room_width/x_multiplier;
    y = room_height/y_multiplier;
}

instance_destroy();

prev_room_width = 240/2
prev_room_height = 320/2
with(all)  
{  
     x = x + prev_room_width - room_width/2
     y = y + prev_room_height - room_height/2
}  

instance_destroy();

___________________________________________
############################################################################################
FATAL ERROR in
action number 1
of Create Event
for object object62:

Push :: Execution Error - Variable Get -1.prev_room_width(100029, -1)
  at gml_Object_object62_Create_0 (line 5) -     x = x + prev_room_width - room_width/2
############################################################################################