1 roommate moving out

[Urban Gillis]

I have 2 roommates who signed a single lease which expires July 31. 1 roommate has moved out and sent me an email giving her "30 days notice" she also paid the july rent. The challenge is the other roommate has not yet decided what she is doing. If the remaining roommate stays they are both still responsible for the full rent? They were good tenants but how do I word a letter letting them both know they are still responsible for the full rent?