We can rewrite the equation of line l in slope-intercept form as y = ¾ x + 7/3, which means the slope of line l is 3/4.
Since perpendicular lines have slopes that are negative reciprocals of each other, the slope of the line we need to find is -4/3.
Substituting into point-slope form,
y + 5 = -4/3 (x - 3)
y + 5 = -4/3 x + 4
y = -4/3 x - 1