How are the coordinates of a new point found if the point is reflected through the line y = x? how are the coordinates of the new point found if the point is reflected through the origin?

The a point is refrected through the line y = x, the new point is found by interchanging the x and y-cordinate of the original point. i.e. if the original point is (a, b) and is refrected through the line y = x, the new point will be (b, a).