Solution: If the drone uses $ \frac38 $ of its battery for 45 minutes, then each $ \frac18 $ of the battery powers $ \frac453 = 15 $ minutes. Thus, the remaining battery is $ \frac58 $, which powers $ 5 \times 15 = 75 $ minutes. Therefore, the remaining flight time is $ \boxed75 $ minutes. - Appfinity Technologies