Answer:
m = - 5/4
Explanation:
If two lines are perpendicular, their slopes are negative reciprocals, which means that their product is -1
We can write the equation
4*x - 5*y + 13 = 0
as: 5*y = 4*x + 13 or
y = (4/5)*x + 13 (1)
Equation (1) is the equation of a straight line in its slope point form, 4/5 is the slope, according to this the slope of a perpendicular line is
-5/4