In a game, Brian scored 6 points on his first move and 9 points on his second move. How many points must he score on his third move so that the average number of points for the 3 moves will be 12?

Atruck can be rented from company a $50 a day plus $0.60 per mile. company b charges $20 a day plus $0.80 per mile to rent the same truck. find the number of miles in a day at which the rental costs for company a and company b are the same