I am 25yo, just had my first and only seizure. i had taken adderall (dextroamphetamine and racemic amphetamine) 12 hours before and marijuana 40 mins before could those cause seizures?

Don't gamble: with your brain, health or life. It's possible, but it's at least as possible, if not more so, that this was what it appears to be: a 1st unprovoked seizure. See a neurologist, don't lie about anything you're taking or using, and do whatever (s)he tells you to do. You may get lucky & have no more; or you may have epilepsy & will have to make some life adjustments.