While you are walking to the synagogue on Shabbat, a Jewish driver stops his car and asks you how to drive to that synagogue. Is there any problem giving him the directions? Are you facilitating or encouraging him to do a melacha?
Rabbi Benjamin Yasgur quotes Nechama Leibowitz, who said that Rabbi Shlomo Zalman Auerbach ruled that yes, you are allowed to give him directions, for two reasons:
If you don't answer, the driver might commit additional violations if they choose the wrong way.
Not answering might create animosity (איבה) between Jews.