Answer
y = -2x + 10
Explanation
The general equation for a straight line is y = mx + c where m and c are gradient and y-intercept respectively.
y=x/2+3 = y (1/2)x + 3
gradient = 1/2
Gradient of the line perpendicular to y=x/2+3 is;
m × 1/2 = -1
m = -2
Now we find the equation of a line passing through (1,8) and have a gradient of -2.
-2 = (y - 8)/(x - 1)
-2(x - 1) = (y - 8)
2 -2x = y - 8
y = -2x + 10
