Can I mix a BS degree with a BA degree when doing a double major?
The short answer is yes, but you certainly want to read carefully the requirements for the double degree. This used to be extremely difficult to do, but in recent years the process has been streamlined enough so that students are beginning to go this route. You probably want to talk to your Economics advisor early on since there will probably be few degrees of freedom when selecting your courses given the constraints / requirements of the two majors.