Help tracking stock needed!

I need to start keeping a track of the small stock of PPE that we keep at our office.

I'm setting up the attached spreadsheet which has two sheets, the first to track who's taking what and why and the second is the master list of stocked items.

I'm trying to get Column D in Sheet 2 to track the remaining stock of each item based on the original amount in stock (Column C). I've tried SUMIFs and VLOOKUPs in Column D to look at each time an item code appears in sheet one and to subtract the numbers being taken from the original stock value.

Hopefully that makes sense because I just can't get anything to work!

Would be extremely grateful if somebody could take a look for me?

Try

in D2

=$C2-SUMIF(Sheet1!$C$2:$C$4,Sheet2!B2,Sheet1!$E$2:$E$4)

Thanks, I had something similar but I'm getting the same result either way. D2 now just equals 50?

Try changing trouser to trousers in B2 !