y = -1/2x - 3....slope here is -1/2. A perpendicular line will have a negative reciprocal slope. All that means is " flip " the slope and change the sign. So we need a slope of 2 for our perpendicular line.
y = mx + b slope(m) = 2 (6,-4)...x = 6 and y = -4 now we sub and find b -4 = 2(6) + b -4 = 12 + b -4 - 12 = b -16 = b