To help find the interval look at the root and act in that key. Example: If it was an Eb to an A. look at it in the key of Eb. Identity the interval not the tonality first. So it would be a 4th. Then, tell if it is major, minor, augmented, or diminished. A perfect interval can be unison, perfect prime (8th), 4th, or 5th. The tonality for a 8th, 4th, or 6th can be perfect (part of the major scale such as Ab in the key of Eb), augmented is a half step up (such as an A) or diminished half step down (such as Abb). If it is a interval of a 2nd, 3rd, 6th, or 7th. Then it can be Major (think major scale). If it is a half step down from the major then it is minor. If it is a whole step down (from the major) it is a diminished. If it is a half step up from the major then it is a augmented cord. Hoped this help and wasn’t too confusing!
