Creating a Conditional Rollup Base

I have two tables, and I want one to display a sum of a column if it meets

Table 1
House # | Free Nights Total | Total Nights Used|
House 1 | 5 | 4 |
House 2 | 3 | 2 |
House 3 | 9 |

Table Two
Guest Name | House # Used | Free Nights Used
Guest 1 | House 1 | 2
Guest 2 | House 3 | 5
Guest 3 | House 1 | 4

What Im looking for is the “Total Nights Used” column in table 1 to total up each Houses used Free Nights

Hopefully that makes sense??? And apologies if this question has already been answered!

I’m not sure if I completely understand your application but I’ve mocked up a quick base. The solution I used was to use a 3rd table, then use rollups to total data.