Sum of each item in a mixed list

Hello, I work in IT and I am trying to create a spreadsheet to keep track of the inventory in our storage room. So far, I have three sheets, named and used as follows:

"Current Totals": (blank at the moment, see below)

"Check In-Out": a running list for my team to add items as they add and subtract stuff from inventory. Column A is date, Column B is Tech name, Column C is the item name, and column D is qty. The Tech and Item columns have data validation from the "Data" sheet so that the Tech and Item names are always the same. Some examples of the item names are: "Laptop - HP ProBook 6530b", "Desktop - Dell OptiPlex 7020", "Printer/Scanner - Fujitsu fi-7160".

"Data": contains a list of all the Tech names for column B in "Check In-Out", and a list of Item names for column C in "Check In-Out".

So here's what I need help with. I want a view on the "Current Totals" sheet that lists each item and shows their current count from the numbers on the "Check In-Out" sheet. I'm just not sure how to go about doing a sum of each item from the list on the "Check In-Out" sheet all in one formula.

Thanks in advance.

Here is the file:

Inventory.xlsx

It looks like that is working, except that I will eventually have negative numbers in column D on the Check In-Out as well as positive. I just tested by adding a -1 qty item, and it added it instead of subtracting it. I made a few changes to the workbook, so I will post it again here.

Inventory.xlsx

Thanks for the help thus far.

That did it, thanks much!