bob sold 425 tickets for a dance. tickets cost $18 per adult and $6 per child. Total receipts were $6450, how many children tickets were sold?
a = adults
c = children
a + c = 425
a = 425 - c
18(425 - c) + 6c = 6450
7650 - 18c + 6c = 6450
-12c = 1,200
c = 100
a + 100 = 425
a = 325