Cap rate on multi house purchase - 2 rentals, 1 primary

[Kathy Moser]

Hi Amazing BP People,

Still negotiating off-market multi-house deal.  Owner says "I look at this as an investment property and base values off 6.25 cap rate."  

The thing is that 2 of the houses are rentals and the third will be my primary residence so I'm not sure how to work that.

Any suggestions on how to think about, calculate, present back to him the cap rate with one house being primary residence?

Thanks!