Proof Primary Residence HouseHack DUPLEX! 2/5 yrs + 2/5 yrs?

[Susan O.]

Hi I'm wondering regarding the 2/5 years for primary residence exemption.  When you are doing a house hack and live in one unit and rent out the others.

There's a $250,000 tax exemption for primary residences/ owner occupancy of a Property.  Usually this is for a owner occ house but this is a duplex

I have a duplex I lived in one side for 2 years while I fixed up the other unit. from 2015-2017

Now I've been living for 2 and a half years  from 2018 to present time in the other unit I originally fixed up.  So would I be able to take 100% of the $250,000 capital gains tax exemption.   The original side i was living in for the first 2 years is now being rented to someone.

What's the proof we have to give when we're owner occupying just 50% or some other portion