difference between two dates

[allems]

Hi... new here and need some help with my worksheet
on column C, i need the difference (from date of admission and discharge) / i used the formula =datedif(d-c) and =d-c / all didnt work; also it would be best if the result highlights less than 2 days. On the column e, i would need the difference between discharge date and dictate date / much similar to the previous columns, and highlight the result of more than 30 days; so it will be easier to recognize the files that are incomplete.

appreciate if anyone can help me out

thank you