to be congruent only translation, rotations and reflections are allowed
1)
(x, y) → (2x, y)=scale->not congruent
(x, y) → (x , y + 7)
(x, y) → (–x, –y)
2)
(x, y) → (x – 5, y)=translation
(x, y) → (x, –y)=reflection
(x, y) → (0.75x, 0.75y)=scale->not congruent
3)
(x, y) → (–x, y)=reflection
(x, y) → (3x, 3y)=scale->not allowed
(x, y) → (x – 9, y)
4)
(x, y) → (–x, –y)=reflection
(x, y) → (x + 4, y)=transformation
(x, y) → (x, y – 1)=transformation
->is congruent
so 4) is a series of transformations with a congruent after image
