Your conclusion should be that I am such a dummy with lisp that I was testing it a wrong way.
I can sometimes be frustrated about simplest things with lisp
In any case I kinda mislead all of you and myself. Since I understood that besides first value of list element I need to compare also second and third values, since some of them might also vary from time to time. So I need to proceed summing last numbers for each first value only in case if I have a match between second and third elements. And if there is a mismatch on the road I need new summing of last numbers to be done and a separate list member to be added in the output.
For example for a list like this:
(("1" "#5" "19" "225") ("1" "
#7" "19" "560") ("1" "#5" "19" "463") ("1" "
#7" "19" "755") ("1" "#5" "19" "1164.75") ("2" "#5" "19" "2653.75") ("2" "#5" "19" "585") ("2" "#5" "
16" "153.75") ("3" "#5" "19" "2653.75") ("3" "#5" "19" "585") ("3" "#5" "19" "227.5"))
I need to receive this:
(("1" "#5" "19" "1852.75") ("1" "
#7" "19" "1315") ("2" "#5" "19" "3238,75") ("2" "#5" "
16" "153.75") ("3" "#5" "19" "3466.25"))
I will try to play with your lisps and will see how long it will take me till I finally realize that I am stuck again