Days formula help

Hi all 

Can someone please help me, I've been trying to make a sort of university work timetable based off of the the Eisenhower matrix. I'm trying to get the H column to show how many days I have left to do an assignment but for some reason, the formula is spitting out a date format and not the number of days below is a pic to try and show what I mean. I'd really appreciate any input as to what exactly I'm doing wrong.