$2)$ Consider the completely parenthesized expression

$(($a $+$ b$)($c $$ d$))*($e $-$: $($f $*($g $$ h$)))$

a$)$ Give the sentence that result from POSTORDER search of the positional binary tree

representing the above parenthesized expression, $/3$ marks$/$

b$)$ Evaluate the expression result after postorder search in postfix $($reverse Polish$)$ form you

find in $($a$).($Consider that: a $=3,$ b $=4,$ c $=7,$ d $=2,$ e $=12,$ f $=3,$ g $=6,$ h $=4)$

$/2$ marks$/$

c$)$ Find the doubly$-$linked$-$list representation. $($Index$,$ Left, Data, Right$)$