Question

The point P' (2, -9) is reflected in the line y=x. What are the coordinates of P'?

Answer 1

You have the point P(2,-9)

When any point is reflected around the line y=x, its coordinaes changes as follow: x coordinate becomes y coordinate, and y coodinate becomes x coordinate.

In this case you have that the reflected point will be:

P' (-9,2)