Implementing Specifications

$($a$)$ Given $\backslash$Sigma $=\{$x$$ R $,$y$$ R $,$z$$ R$\},$ implement $($using forward substitution$)$ the following specification using a sequence of $($nonparallel$)$ assignments.

$($x$,$ y$)=($xm$2+$ x $+$ my$,$ y $+$ mx$)$

$($b$)$ Use the alternation law to implement the following.

$\{$x$,$ y$,$ z$\}=\{$x$,$ y$,$ z$\}$ x$<=$ y$<=$ z$$