Suppose that $\backslash ($ z $\backslash )$ is a linear function of $\backslash ($ x $\backslash )$ and $\backslash ($ y $\backslash )$ with slope $7$ in the $\backslash ($ x $\backslash )-$direction and slope $4$ in the $\backslash ($ y $\backslash )-$direction. A change of $0\mathrm{.}5$ in $\backslash ($ x $\backslash )$ and $-0\mathrm{.}3$ in $\backslash ($ y $\backslash )$ produces what change in $\backslash ($ z $\backslash )?$

The change in $\backslash ($ z $\backslash )$ is