Answer:
First, he would decide which one is more important. The football game or the car?
Then after that, if he decided the football game was more important he would go to the football game.
But if he decided that he wanted the car more, he would study for his math test and make sure that he's ready for it.
I think that he would decide that the car and his grades are more important. He will always have another chance to go to a football game. Also if he didn't go, he could get a car and his grades would still be good. That's more important than a football game.