Step-by-step explanation:
To determine distances, we need to use this formula: 
To apply that formula we need to use the coordinates of point, but in this case will be calculated generally, due to the lack of specific values.
So, Point A have the coordinates 
Let's call Point P the one that's on the x-axis, its coordinates are 
Applying the formula, the distance between this two points will be:

To find an opposite and equidistant point, we only need to use opposite values. So, let's call Point B, the opposite point, its coordinates will be:

And the distance will be the same, because squared values will always results positive.