Respuesta :
a = adult
c = children
a + c = 1020 so a= 1020 - c
9a + 4c = 7680
substitute a= 1020 - c into 9a + 4c = 7680
9a + 4c = 7680
9(1020 - c) + 4c = 7680
9180 - 9c + 4c = 7680
-5c = -1500
c = 300
a= 1020 - c
a = 1020 - 300
a = 720
answer: 720 adult tickets were sold
c = children
a + c = 1020 so a= 1020 - c
9a + 4c = 7680
substitute a= 1020 - c into 9a + 4c = 7680
9a + 4c = 7680
9(1020 - c) + 4c = 7680
9180 - 9c + 4c = 7680
-5c = -1500
c = 300
a= 1020 - c
a = 1020 - 300
a = 720
answer: 720 adult tickets were sold
