The school band collected $2,892 for 480 tickets sold to their spring concert. Adult tickets were $8 each and student tickets were $5 each. How many adult tickets were sold?

a + s = 480......s = 480 - a
8a + 5s = 2892

8a + 5(480 - a) = 2892
8a + 2400 - 5a = 2892
8a - 5a = 2892 - 2400
3a = 492
a = 492/3
a = 164 <=== there were 164 adult tickets sold