Question 523219
3y + 21 = 2x

3y=2x-21
/3
y=(2/3)x-7
slope m1= (2/3)
-----
2y = 16 - 3x
/2
y=(-3/2)x +8

slope m2= (-3/2)

The slopes are negative reciprocals

 m1*m2=-1

(-3/2)*(2/3)=-1

So the lines are perpendicular