Find the equation of the perpendicular bisector

How do you find the equation of the perpendicular bisector of the...
#"a perpendicularbisector, bisects a line segment at"# #"right angles"#. #"to obtain theequation we require slope and a point on it"#. #"findthe midpoint and slope ofthe given points"#.

Finding the equation of a perpendicular bisector - Forum
From this point I am asked to findtheequationoftheperpendicularbisector AB. I have looked at the only given example in the coursebook and must say that to me it is very unclear, even the fractions they use when worked out don't equate to the.

Equation of Perpendicular Bisector
Theperpendicularbisector of a line segment is the locus of points on the plane that are equidistant from the endpoints. Example. Findtheequationoftheperpendicularbisectorofthe line segment with endpoints A = (2, 5) and B = (4, −7).