4x - 3y = 0
-3y = -4x
y = (-4/-3)x
y = 4/3x....so ur slope is 4/3....a perpendicular line will have a negative reciprocal slope...all that means is " flip " ur slope and change the sign...so the slope we need is -3/4 (see how I flipped the slope and changed the sign)
y = mx + b
slope(m) = -3/4
(3,-8)...x = 3 and y = -8
now we sub and solve for b, the y intercept
-8 = -3/4(3) + b
-8 = -9/4 + b
-8 + 9/4 = b
- 32/4 + 9/4 = b
- 23/4 = b
so ur perpendicular equation is : y = -3/4x - 23/4