Mike D. answered 01/15/20
18+ Years Exp. Math Tutoring; Data Scientist + LookML/Python Engineer
So first, let's find the slope of the new line.
The original line's slope is 4/3. Perpendicular lines have a negative reciprocal slope, so the new line's slope will be -3/4.
Since we have a slope and we know a point that the line passes through, point-slope form would be the easiest way to write the equation:
y - y1 = m(x - x1)
Substitute (x1, y1) for your point (-4, -1):
y - (-1) = m(x - (-4))
y + 1 = m(x + 4)
Then plug in your slope, and you're done:
y + 1 = -(3/4)(x + 4)