Placing object based on different variables

Question

I am making a game library using SFML.Net , and I want to be able to place a 50x50 tile onto the screen.
I have the Window width, the Window height, the MouseX/MouseY, and an offset based on a custom camera . When WASD is pressed, the offset is potentially added/subtracted 0.5 pixels.

So, I need to know how to get the mouseX, relative to all of these variables, so I can place a tile with the illusion of it being where the user mouse-pressed.

I have tried the code below.
Note: Game.Instance.Scenes[Game.Instance.CurrentScene].Camera.Offset is the camera offset.

 public static float MouseX = 0;
        public static float MouseY = 0;
        public static float MouseXRelative = 0;
        public static float MouseYRelative = 0;

        public static void UpdateRelative()
        {
            MouseXRelative = MouseX + Game.Instance.Scenes[Game.Instance.CurrentScene].Camera.Offset.X;
            MouseYRelative = MouseY + Game.Instance.Scenes[Game.Instance.CurrentScene].Camera.Offset.Y;
        }

And this code below.
Note: this detects when the left mouse button is pressed, and then creates a GameObject, MyGO , **and positions it based on the MouseX/MouseY and offset. Also, RoundTo() is a simple extension method I made to allow the ability to round to a certain number.

if (MouseHandle.LeftButtonDown)
            {
                float x = MouseHandle.MouseX.RoundTo(50) + Game.Instance.Scenes[Game.Instance.CurrentScene].Camera.Offset.X;
                float y = MouseHandle.MouseY.RoundTo(50) + Game.Instance.Scenes[Game.Instance.CurrentScene].Camera.Offset.Y;

                MyGO gm3 = new MyGO();
                gm3.SetPosition(x, y);
                Game.Instance.Scenes[Game.Instance.CurrentScene].Add(gm3);
            }

Answer 1

I have found an answer. What you need to do is use this code I wrote:

public static void UpdateRelative(int rt, bool doRound = false)
        {
            float hw = Game.Instance.Width / 2;
            float hh = Game.Instance.Height / 2;
            Vector2f CameraCenter = new Vector2f();
            CameraCenter.X = hw;
            CameraCenter.Y = hh;

            float diffx;
            float diffy;

            MouseXRelative = CameraCenter.X - MouseX;
            MouseYRelative = CameraCenter.Y - MouseY;

            if (doRound)
            {
                MouseXRelative.RoundTo(rt);
                MouseYRelative.RoundTo(rt);
            }

            diffx = MouseXRelative - MouseX;
            diffy = MouseYRelative - MouseY;

            MouseXRelative = MouseXRelative - diffx;
            MouseYRelative = MouseYRelative - diffy;
        }