In this situation I, (also being 17), would ask a friend from the prior engagement to give me a ride to said engagement. If it is within easy bicycling distance, that works too, but it would seem it is not, (traffic wouldn't stop me but distance definitely would). Honestly, those parents-forced grown-up parties are boring and awkward. A bunch of people at least twenty years older than you who know things about you through your parents is really not a fun activity.

Terrible grammar aside, either get a ride from a friend to the fun thing or stay home and play zelda.