y = 1/2x + 5...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 our perpendicular slope is -2/1 or just -2 (see how I flipped the slope and changed the sign)
y = mx + b
slope(m) = -2
y int (b) = -2
so ur equation is : y = -2x - 2