If this your first, a flip may be a viable option so you can build up some reserves. 

Hey @Mohammad Al-hadad,The first thing I would say is that the cool thing about real estate investing is that there are many options and styles about how to invest and what strategies you want to pursue.

Hey jeremy, sometimes the best options may not be local I recommend asking some qualified investment focused brokers 

If sales price is 400k and I want 75k cash but tenets only can provide 15k, what are my options?

You will then have a few options with that rent money....you can put it into principal or you can start saving it to purchase yet another property.

Real estate investors have a variety of financing options available to them, depending on their financial situation, investment strategy, and the type of property they're interested in.

., seller financing, lease options, etc.)?

Certain suburbs don't have many options for multifamily, so you might have to open your search to other locations.

I would probably have to return the down payment and option money to the end buyer, and he is probably going to sue me.

If not, do I have any other options at 20% down?