Looking at duplex with tenant not paying rent in full.

[Dylan D.]

Im in pennsylvania and I looked at a duplex today. While checking out the property there was 2 main concerns. 1 the floor joists were I'm rough shape. 2 when walking through one of the units we asked the tenant what there rent was. They said they are unsure what it currently is because they have section 8 which covers 800$ and they believe the total is 1200, which tells me they are not paying in full. The numbers work even if they would only pay 800, that being said I would still like them out. I'm just wondering how more experienced investors would handle this as this would be my first deal. My plan was to make an offer at full price with an agreement that that person is removed.