Perpendicular = opposite sign and reciprocal slope
Make equation into y = mx + b
Add 3y to both sides
3y + 54 = 3x
Subtract 54
3y = 3x - 54
Divide by 3
y = x - 18
The slope is 1
Make it negative and reciprocal
= -1/1 = -1
Solution: the slope will be -1