How can I use Monday like Excel and create subtotals for sets of rows (items & subitems)?

I’ve created a board to track a grant budget. I use rows (items) for each budget line item. Then I’m using subitems to track each invoice against the budget line item.
However, I have to report on this grant every quarter, so I need a way to see a subtotal of a group of subitems, to check against my grant report.
It’s a fairly simple task in a spreadsheet.
Can Monday do this?