Final answer:
Rotating 180° and 270° clockwise are not equivalent transformations to the original sequence, but reflecting △ABC across the y-axis is an equivalent transformation.
Step-by-step explanation:
1. Rotating △ABC 180° clockwise is false because when a figure is rotated 180° clockwise, the vertices will end up in different positions than when it is rotated 90° counterclockwise, reflected across the x-axis, and then reflected across the y-axis.
2. Rotating △ABC 270° clockwise is false because when a figure is rotated 270° clockwise, the vertices will end up in different positions than when it is rotated 90° counterclockwise, reflected across the x-axis, and then reflected across the y-axis.
3. Reflecting △ABC across the y-axis is true because reflecting a figure across the y-axis is the same as reflecting it across the x-axis and then rotating it 180° counterclockwise.