Answer:
Yes
Step-by-step explanation:
If they're perpendicular, that means that angle ECM = 90 degrees and angle ACE = 90 degrees. To figure out if this works, plug that into the two equations they give:
ECM = 3x + 15
becomes
90 = 3x + 15
75 = 3x
25 = x
ACE = 4x - 10
becomes
90 = 4x - 10
100 = 4x
25 = x
Since you get x = 25 for both, you know that they are perpendicular because they both measure 90 degrees
The slope point form is

m is the slope
x1, y1 are the coordinates of a point on the line
The slope of the line is -1
m = -1
point (-5, -4) lies on the line
x1 = -5 and y1 = -4
Let us substitute them in the form above

Remember (-)(-) = (+)

The equation of the line in the slope-point form is y + 4 = -1(x + 5)
It would be 480, because I did it in Desmos