1. If I (took) it to the police station, they (wouldn't be) interested.
2. If I (asked) in the nearest shop, the assistant (might say) it was hers.
3. If I (gave) it to a homeless person, they (would spend) it on beer.
4. If I (told) my friends, they (would want) to spend it and if I (kept) it, I (might feel) guilty. I hope I'd never find €100 in the street.