The line we want has a slope that is the negative reciprocal of the slope of the line
y = -(1/2)x - 5
The slope of this line is -1/2. So, the slope of its perpendicular lines is 2. Therefore, their equations have the form:
y = 2x + b
Now, to find b, we use the values of the coordinates of the point (6, -4) in that equation:
-4 = 2*6 + b
-4 = 12 + b
b = -4 - 12 = -16
Therefore, the equation is y = 2x - 16.