#### Answer

$\color{blue}{y=\frac{3}{2}xz}$

#### Work Step by Step

RECALL:
When $y$ varies jointly as $x$ and $z$, the variation is represented by the equation $y=kxz$ where $k$ is the constant of variation.
$y$ varies jointly as $x$ and $z$ so the equation of the variation is $y=kxz$ with $k$=constant of variation. To find the value of $k$, substitute the given values into $y=kxz$ to obtain:
$$y=kxz
\\105=k(14)(5)
\\105=70k
\\\frac{105}{70}=\frac{70k}{70}
\\\frac{3}{2}=k$$
Thus, the equation of the variation is: $\color{blue}{y=\frac{3}{2}xz}$.