There should be 480 visitors (including children)
This would be because 60% of the people have 180 children so divide by 6 and you have 30 or 10%, multiply the 30 by 10 (to get a hundred percent [300] ) and add the children to get 480.
Wait wouldn't you only subtract the numbers so it would be 240000-60000 I'm not really sure I'm not the best with math so don't take my word for it I'm sorry if I did it wrong