Explanation:
x = number of adult tickets
y = number of student tickets
x + y = 412
x = 412 - y
5x + 3y = 1584
now, we use the first equation/ identity in the second equation and get
5(412 - y) + 3y = 1584
2060 - 5y + 3y = 1584
2060 - 2y = 1584
476 - 2y = 0
476 = 2y
y = 476/2 = 238
x = 412 - y = 412 - 238 = 174
so,
174 adult tickets and 238 student tickets were sold.