Answer:
56 adult tickets were sold that day
Explanation:
let a represent number of adult tickets sold and c number of child tickets sold , then
a + c = 122 → (1)
9.1a + 5.7c = 885.8 → (2)
from (1) subtract c from both sides
c = 122 - a
substitute c = 122 - a into (2)
9.1a + 5.7(122 - a) = 885.8
9.1a + 695.4 - 5.7a = 885.8
3.4a + 695.4 = 885.8 ( subtract 695.4 from both sides )
3.4a = 190.4 ( divide both sides by 3.4 )
a = 56
that is 56 adult tickets were sold that day.