Answer:
27 children.
Step-by-step explanation:
For every 9 children there are 4 adults .
x + y = 39 where x = number of children and y = number of adults.
and x/y = 9/4
so 4x = 9y
then x = 9y/4 , so substituting for x in the first equation:-
y + 9y/4 = 39 Multiplying through by 4:-
4y + 9y = 156
y = 156/13 = 12 so there are 12 adults
and 39 - 12 = 27 children