ANSWER
P'(6,-1)
EXPLANATION
The mapping for a reflection in the line y=x is
The line y=x is the mirror line for a function and it's inverse.
[tex](x,y)\to (y,x)[/tex]
The x and y coordinates swap position.
The reflection of point P(−1, 6) across the line y = x is
P'(6,-1)
