The simplest passing efficiency rate: a passer's gross passing yards divided by his pass attempts. In official NFL scoring a sack is not a pass attempt, and an individual passer's yards do not have sack yardage subtracted (team net passing yards do).
Adjusted yards per attempt (AY/A) adds 20 yards for every touchdown pass and subtracts 45 for every interception, so scoring and turnovers move the number.