Formula Field change based on 3-4 fields

I Need a Formula Text Field titled Eligibility with 2 possible options (Eligible and Ineligible).

Someone is eligible based on the following responses

Eligible 

1. [Are you a Resident] = Yes
2. [# of days since last service] >or=365 or null
3. [Are you at least 30 days behind on Rent] = Yes
4. [Age] > or = 18


Someone is Ineligible based on the following responses

Ineligible 

1. Are you a Resident = No
2. # of days since last service < 365
3. Are you at least 30 days behind on Rent = No
4. [Age] < 18