Answer:
150 adults, 270 kids.
Explanation:
We can make a set of equations with the given information:
Adult=X
Kids=Y
3x+1y=720
x=y=420
420-X=Y
3x+420-x=720
2x+420=720 720-420=300
300/2=150
X=150, there were 150 adult visitors which means there are 270 children