jeff has 4 hours that he can choose to spend either studying for a test or playing a new video game. If he spends all of time studying, he can score a 92 on the test. If he plays for 1 hour, his test score falls 5 points. For playing a second hour, his score falls by 7 points. Playing for a third hour will lower his score by another 10 points. Jeff's PPC for test score versus hours playing his new video game is