During combat, each unit inflicts its combat value in damage points (DP). 6 DP kills a unit (or inflicts a hit on a 2-step unit). Damage must be inflicted against already damaged units if possible.
At the end of the battle, any attacking unit with 3+ DP is removed.
For AA, multiply the combat value by the number of targets.
Strategic bombing inflicts 3.5 IPC damage each if no AA, and 1 IPC damage if there is AA. In versions of A&A using fighter interceptors, resolve combat normally, with each surviving Bomber inflicting 3.5 damage. In either case, round halves down.
2 Infantry + 1 Fighter vs 1 Infantry + AA Gun
Round 0: AA Gun inflicts 1 DP on fighter
Round 1: Attackers inflict 5 DP on Infantry. Defenders inflict 2 more DP on fighter.
Round 2: Attacker destroys defending infantry. Defender inflicts 2 more DP on fighter.
The fighter now has 5 DP and is removed.