John wants to spend the Saturday outside with his kids and their friends, but he can't decide what to do. He asks his kids and t
heir buddies to see what they are interested in. 10 children want to go to the beach, 8 want to stay at the pool, and 15 want to go to the water-park. 4 of those children want to go to the pool and the water-park. 6 want to go to the water-park and the beach, and 2 want to go to the pool and the beach. 1 child wants to fit in all three. How many children does John plan to spend the day with?