Find an Equation of Variation for the Given Situation $y = \frac { 18 } { x Z }$

Multiple Choice

Find an equation of variation for the given situation.
- y varies jointly as x and z , and y=18 when x=3 and z=3

A) y=6 x
B) y=4 x z
C) $y = \frac { 18 } { x Z }$
D) y=2 x z