They sell children’s 30 tickets and  70 adult’s tickets.
Explanation:
Let the number of child’s tickets=x
Number of adult’s tickets sold=y
Charge of child’s ticket=$6
Total number of tickets sold=100
Charge of adult’s ticket=$10
Total money made by selling tickets=$880
We have to represent the following situations in the form of two equations
Considering the number of tickets sold, we get the equation
x+y=100 Â
considering the  total money made by selling tickets
we get the equation 6x+10y=880 Â
we can solve this set of linear equations using
elimination method
x+y=100 (1)
6x+10y=880(2)
(1)*6
6x+6y=600 (3)
6x+10y=880(4)
(4)-(3)
6x+10y-6x-6y=880-600 Â
4y=280 Â
y=280/4=70 Â
substitute the value of in (1) Â
x+70=100 Â
x=30