Best check the Bryant website. I know of no way to find the seer rating by the name plate unless it is listed. A package unit will be close to the SEER ratings a split system could be lower because of installation issues.
Age will have a lot to do with the SEER. If your home is newer than 1995 then the unit is a 10 SEER minimum. If the unit is older than 1995,,,, well you get the idea.
I offer this as a help to determine if you can save any money by changing out the unit.
http://198.147.238.24/ac_calc/default.asp Notice that changing the insulation of the ducts will have a positive effect.