How to link to totals from 3 tables in 4th table?

I have 3 tables: Budget, Liabilities, Projections. All have different columns, but there is one Total column in each table for multiple items, and I want to link to the sum of that Total column.

Example: Budget = $5,000; Liabilities = $2,000; Projections = $15,000. I want the Overview to have a row for each, with that sum value in a column.

I want to have a 4th table (Overview) with 3 rows, one for each table, and one column linking the Total from each table, that’s it. How can I do this? I’ve been able to use rollup but I need a separate column for each table and it looks odd. Any way to have one column showing the Total from each table on the 4th table?