subject to deal, should i pay seller profits?

[Jeffery Leroy]

thanks for hear me out.. adding the seller recently lost their spouse.

these are the round numbers for the sake of the detail. they're selling a duplex for 70k, owe about 40k and will make about 30k in profit, the property is valued at 110k with no repairs needed and two tenants paying on time $1100 total per month.

should i pay them their profit of the 30k (or part of it) keep their current mortgage which they've had for about 20yrs with low payment and interest? or get a new 30 year vs their 10 yrs left on current..