Looking to wholesale my moms rental property

[Jesse Watts]

My mother has a rental property that she let extended family stay in and they completely trashed the place and didn't pay for a number of months. My mother lives out of state and can not pay the necessary amount to get the mortgage caught up. So I have been looking to start my wholesale journey and was wondering if I was looking at this possible deal correctly. 

So I would take the ARV (ARV is the same as comps correct?) and subtract it by 30% and thats my price I look to offer the buyer. Then I subtract the amount of mortgage owned and rehab costs to get a number. Then I subtract that number buy the amount of money I want to make and thats the number I would offer my mother for the house. Is that correct? Thank you all for your help on understanding the numbers.