slope = - 2, midpoint = (2, - 2 )
the slope m is calculated using the ' gradient formula '
m = ( y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = (4, - 6 ) and (x₂, y₂ ) = (0, 2 )
m = 
 =
 = 
 = - 2
 = - 2
calculate midpoint using midpoint formula
{
 (4 + 0 ),
 (4 + 0 ), 
 (- 6 + 2 )] = (2, - 2 )
 (- 6 + 2 )] = (2, - 2 )
gradient of perpendicular bisector = - 
 =
 = 

equation in slope-intercept form is 
y = mx + c ( m is slope and c the y-intercept )
partial equation is y = 
 x + c
 x + c
to find c substitute ( 2, - 2) into the partial equation
- 2 = 1 + c ⇒ c = - 3
y = 
 x - 3 in slope-intercept form
 x - 3 in slope-intercept form