Find the Variation Equation for the Variation Statement $z$ Varies Directly As

Multiple Choice

Find the variation equation for the variation statement.
- $z$ varies directly as $x$ and inversely as $y ; z = 5$ when $x = 45$ and $y = 45$

A) $z = \frac { 5 } { x y }$
B) $z = \frac { 5 x } { y }$
C) $z = \frac { x } { 5 y }$
D) $z = 5 x y$