Answer:
 will be the slope of the line perpendicular to xy.
Explanation:
The equation of line xy is ( y-3 ) = 
 (x-4)
y = 
 ( x-4 ) + 3
y = 
 x + 
 + 3
y = 
 x + 

So the line has slope = 
 and y-intercept = 
.
Let m is the slope of a line perpendicular to line xy.
We know that for perpendicular lines having slopes m₁ and m₂
m₁ × m₂ = -1
Therefore, for m₁ = m and m₂ = 

mx (
) = -1
m = (
)
 will be the slope of the line perpendicular to xy.