Rotation 90
(x,y)->(-y,x)
Rotation 180
(x,y)->(-x,-y)
Rotation 270
(x,y)->(y,-x)
Reflection Across Y-Axis
(x,y)->(-x,y)
Reflection Across X-Axis
(x,y)->(x,-y)
Reflection Across Y=X
(x,y)->(y,x)
Reflection Across Y=-X
(x,y)->(-y,-x)
Translation
(x,y)->(x+a,y+b)