In the beyond the sea episode, Noah guessed that Dr Holiday is about 28.
As for Beverly the event was about 5 years ago. In the family Holiday episode Rebecca stated that Beverly went EVO at age 13. I'd guess probably about a year passes between those two episodes, so Holiday is now about 29 and Rex has been with providence about 2 years. Beverly was an EVO before he came, so she's been EVO for 2-3 years at least. but she could have been EVO for as much as 6 or 7. Beverly should be about 15 -20 now, and that makes her about 9-14 years younger than Rebecca. give or take a year or two and assuming Noah really knows Holiday's age, which is unlikely.