Since line m is the perpendicular bisector of segment AB, the value of x is equal to 34 units.
In Mathematics and Geometry, a perpendicular bisector is a segment, or ray that bisects or divides a line segment exactly into two (2) equal halves and forms an angle that has a magnitude of 90 degrees at the point of intersection.
Based on the definition of a perpendicular bisector, we can logically deduce the following congruent sides;
3x + 77 = 6x - 25
6x - 3x = 77 + 25
3x = 102
x = 102/3
x = 34 units.