$(10$ points$)$

a$.(4$ points$)$ Construct the labeled tree representing the algebraic expression

$\frac{(x-2)+(3+y)}{(2-(3+z))**(w+8)}$

b$.(2$ points$)$ Write the result of performing a preorder search for the tree

$(4$ points$)$ Suppose that $x=6,y=3,z=3,$ and $w=6,$ evaluate the expression in Polish form notation.