At the movie theatre, child admission is $6.00 and adult admission is $9.10. On Friday, three times as many adult tickets as child tickets were sold, for a total sales of $999.00. How many child tickets were sold that day?

30 child tickets

Step-by-step explanation:

Let the number of children in the theater on Friday be c

as given that the number of adults on Friday in the theater is 3 times that of number of children

Hence number of adults = 3c

Cost of adults ticket = 9.10

cost of child ticket = 6

total cost = 9.1 (3c) + 6c = 999

hence

27.3c+6c=999

33.3c=999

dividing both sides by 33.3

c=30

Hence there were 30 children in theater on Friday