How do I tackle this problem?

Your wonderful typography does not communicate the value of the slope of your line. If that slope is "m", then the equation of the perpendicular line through the point can be written using point-slope form as
.. y = (-1/m)(x +4) -1
You can simplify or choose a different form as you may desire.

If your line is
.. y = 4/5x -1
the line you want is
.. y = -5/4(x +4) -1
.. y = (-5/4)x -6 . . . . simplified to slope-intercept form
.. 5x +4y = -24 . . . rearranged to standard form


If your line is
.. y = -4/5x -1
the line you want is
.. y = 5/4(x +4) -1
.. y = (5/4)x +4 . . . . simplified to slope-intercept form
.. 5x -4y = -16 . . . .rearranged to standard form

what's " graph of
y = −
4
5
x − 1" ?