Rectangle ABCD is reflected over the y-axis. What is the rule for the reflection, and what is the new coordinate of A'?

Question

A (-5, 1), B (-5, 3), C (-1, 3), and D (-1, 3) 

Answer 1

The rule for the reflection around the Y axis is you basically just put a "negative" in front of the X coordinates of each point.  If a point is, say, 2 units away from the Y axis in the positive direction, its reflection across the Y axis would be 2 units from the Y axis in the negative direction.

 

In this case, since all you care about is the point "A", you can disregard all the other points.  Point A is at (-5, 1), meaning it is -5 units away from the Y axis.  Jump to the other side of Y, it will be (5,1).