Discount Cash Offer w/ Mortgage Balance

[Shantel James]

What happens when you offer a discounted cash offer but a balance still remains on the mortgage?  Is that even possible?  For example, you have a motivated seller that owes $110K on the home.  He needs to sell because can't afford payments, had a lot of bad things happen during the year (in the house), and has found a job out of state to get away/start over and just wants out (whatever the reason, he is motivated). A fair offer due to market value and repairs ends up being $90K (leaving a $20K difference).  The seller is motivated enough to carry the $20K, but can the owner/seller accept this offer?  What would it look like?  Does this ever really happen?  Is this even a real deal? 

Just trying to work out offers/deal strategies and don't want to miss any that could be viable possibilities.  Thanks in advance...