y= -x/2 + b
3 =2/2 + b
b = 3-1 = 2
y=-x/2 + 2 is the perpendicular line through the given point
general equation is y=mx + b where m=slope and b = y intercept
perpendicular line's slope is the negative inverse. -1/2 is the negative inverse of 2
change the sign and flip it upside down 2/1 to 1/2 with a negative sign