Correct statements are:
If it is reflected across the y-axis, its length still will be 12 units.
If it is rotated 270° about the origin, its length still will be 12 units.
If it is translated 15 units up, its length still will be 12 units.
<u>Step-by-step explanation:</u>
Whatever it may be rotation, reflection or translation, the size of the line will never change. So length of the line is same as 12 units in the image.
So the wrong statements are
If its reflected across y = -x then the length will no longer be 12 units.
If it is rotated 90° about the origin, then the length will no longer be 12 units.
If it is translated 18 units to the right, then the length will no longer be 12 units.
The slope of the line is 3/2. That would be letter B. You take two points from the graph and subtract them from each other to find the slope. Hope this helps!
