Hi guys i have to fit a back to wall toilet pan and it comes with some sort of 'L" shaped plastic brackets to screw into the floor and then the toilet pan hides those brackets ( which are not exactly 90 degrees but roughly 80 degrees) and screws into those brackets sideways. I have never fitted a toilet to the floor like that so any advice on how to measure where and how to screw them would be greatly appreciated. The floor is tiled and tiles have been laid on plywood. Thank you very much for your help.