Common Lisp

I will post my implementation in a couple days. May the best EXPERT PROGRAMMER win

Write the function
simplify (x)
returns an expression in which constants have been combined and unnecessary operators have been
removed. x is a valid arithmetic LISP expression involving only the operators "+" and "*". Examples:
Expression Returns
(simplify ’a) a
(simplify ’(*)) 1
(simplify ’(+ a)) a
(simplify ’(* 1 a 1 1 1)) a
(simplify ’(* 8 7)) 56
(simplify ’(* 3 0 4)) 0
(simplify ’(+ a 1 2 b)) (+ 3 a b)
(simplify ’(* 4 (+ 2 3) (+ 1 2 3) (* 2 3))) 720
(simplify ’(+ 4 (+ 2 3 b) (+ 1 2 c 3) (* 2 3))) (+ 10 (+ 5 b) (+ 6 c))
(simplify ’(* 4 (+ 2 3 b) (+ 1 2 c 3) (* 2 3))) (* 24 (+ 5 b) (+ 6 c))
Note how constants are combined or eliminated whenever possible, and how the simplifications apply
recursively. Also note that adjacent unsimplifiable expressions are not combined; e.g., in the second to
last expression, the "+" operators are not combined to
(+ 21 b c)
That form of simplification is beyond this program. See the correct output for more examples.
Part 4:

OP Here, forgot to mention the stuff to the right of the calls is sample output.
Also

NO ITERATION, NO DESTRUCTIVE CALLS
SOLUTION MUST BE RECURSIVE OR USE FUNCTION MAPPING