Answer:
It seems to just mess around with the positive and negatives.
Explanation:
When you flip an object by the x axis, the x part of the coordinates (x, y) would become negative, or if already negative, positive. Try it yourself, by taking point be, and counting down to the line of the x axis. Remember the number down you counted, and count that same number down from the x axis. That is mirroring a point.