Seller financing terms

[William Weaverling]

Hey everyone! Im looking for help coming up with seller financing terms on a triplex. I asked the owner if they would be up for seller financing and they said depends on the terms. So I’m wondering how to calculate and come up with terms. The formation on the property is below.

Existing Building: 2,452 Sq Ft

Lot Size: 25 x 120 | 2,831 Sq Ft

1ST Floor:

1 Bed, 1 Bath

Monthly Income $550

2ND Floor:

2 Bed, 1 Bath

Monthly Income: $900

3RD Floor:

2 Bed, 1 Bath

Monthly Income: $850

Asking: $240,000

I believe rent is under market value. I would also like to put down as minimum as possible. Thanks