3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 #lang racket ; to use set-car! set-cdr! (require r5rs) (define (count-pairs lst) (let ((counted '())) (define (counter x) (if (or (not (pair? x)) (memq x counted)) 0 (begin (set! counted (cons x …