Posted by Janet on .
A music concert was attended by 450 people. Adult tickets sold for $70 and childrenâ€™s tickets for $40. If total sales were $27,750, how much of each ticket was sold?

math 
Kuai,
Adult: a
Children: c
a + c = 450
70a + 40c = 27750
Substitute
c = 450 a
70a + 40(450  a) = 27750
70a + 18000 40a = 27750
30a + 18000 = 27750
30a + 18000 18000= 2775018000
30a = 9750
30a/30 = 9750/30
a = 325
c = 450 a
c = 450325
c = 125