Investors & landlords

If the property was rented in 2019 and sold in 2019 I realize it has to be reported. Must this be done in BOTH 

  • Under the rental section 
  • Under the sale of business property 

Also, the house was sold for a capital gain but a large amount of the sale price paid off a mortgage which was outstanding on the property. So the amount realized was far smaller. What entry takes this into account and where does that go in? Capital gain may not be affected but income from sale is massively lower than the market sale value.

Thanks