The set of points that are equidistant from A = (7,3) and B = (1,7) is the perpendicular bisector of line segment AB.
Slope of AB = (7-3) / (1-7) = -2/3
So, slope of perpendicular bisector = -1 / (-2/3) = 3/2
Perpendicular bisector passes through the midpoint of AB. Midpoint of AB = ( (7+1)/2, (3+7)/2 ) = (4, 5)
Equation of perpendicular bisector: y - 5 = (3/2)(x - 4)
y - 5 = (3/2)x - 6
y = (3/2)x - 1
On the x-axis, y = 0. So, 0 = (3/2)x - 1
1 = (3/2)x x = 2/3
The point on the x-axis equidistant form (7,3) and (1,7) is (2/3, 0).