Slope of ON = -4-0/3-0 = -4/3
Since line L ⊥ ON,
slope of the line L is 3/4 and it passes through point N (3, 4).
Equation of the line in slope point form is y – y1 = m(x – x1)
Equation of line L is y-(-4) = 3/4 (x-3)
∴ 4(y + 4) = 3(x – 3)
∴ 4y + 16 = 3x – 9
∴ 3x – 4y – 25 = 0