Actually I think I should be able to solve this myself, but I'm running out of time.
With this code all items in two lists are added:
(mapcar '+ '(1 2 3 4 5) '(1 2 3 4 5))
But I would like to add all items of lists in a list:
((1 2 3 4 5) (1 2 3 4 5) (1 2 3 4 5) (1 2 3 4 5))
to get:
(4 8 12 16 25)
I'm sure it must be easy, but please help me out. The lists in the list are always the same length.