1031 on a primary residence/rental 2 family

[John Kaspar]

I currently have a 2 family that I rent half out. I purchased it for 400 expecting to sell it for 600. When I sell, how would capital gains work out? Would it be half of the property due to it being half an investment? Or 100% due to it being my property. Also, I did some digging and certain people articles had to be worth more than the previous property and one said it had to just utilize all of the capital I just accrued.

I feel like this is worded awkwardly.