A suffix is added at the end of a given word while the prefix is added the beginning of the given word.
inaddable. The prefix in is used and also the suffix Able.
You could add the suffix -s to it to make the word isles.
infavorable
You could add the prefix re- and the suffix -ing to make the word renumbering.
You could add the prefix -un and the suffix -ed to make the word "un-vindicated."
unhelpful
It doesn't currently, but you could add the prefix up- or the suffix -ed to make the words "upsurge" and "surged."
The prefix for bank is pre and the sufix is ed
You could add the prefix un- to it to make the word unreliable.
stem
The word "lady" has no prefix or suffix; you can add one to make ladybug, or unladylike.
The word is from the Latin crepare meaning rattle. The suffix -itus makes it into a noun. No prefix. You can add the prefix de- to make the word "decrepit."