How to Input total number from user input table by filtering the same name or ID

[dafarpr]

Hello, please help. I can't find the solution for this formula. it's for the inventory system, input by a registered user. it can count how many items are left in the inventory

here's the item table

I want it when someone borrows something the amount of items it was input by the user will go to the item table in the "Jumlah Pinjam" row the data is called in the slice process.

Please help me solve this. thank you