DrScheme, version 4.2.5

> (define (sum-square-max a b c) (if (and (>= a c) (>= b c)) (+ (* a a) (* b B)/>/>) (sum-square-max c a B)/>/>))

Also, I tried ending the procedure with

(sum-square-max c a B)/>/>))and Scheme sits there thinking for eternity, why?