For senior night, the vollyball team sold 850 tickets for the big game and made 6050 dollars. If the presale tickets were 5 dollars and the tickets at the door were 9 dollars, how many tickets were sold at the door?
+237 presale = p
door = d
(1) p + d = 850
(2) 5p + 9d = 6050
(1) * 5 = 5p +5d = 4250
(2)- (1) = 4d = 1800
d = 450 tickets
