1. There is a pound of candy in three packages. The first package has by weight not less candy than the second one, and the second package has by weight not less candy than the third. What is the maximal possible amount of candy in the third package?
2. Find a and b if a - b = 5 and a/b = 5.
3. Present 12 as a sum of positive integers such that their product is maximal.
4. Place 7 points on the plane so that among any three of them at least two are at the distance of 1 from each other.
5. Paint a plane with nine colors so that any two points at the distance of 1 from each other would be of different colors.
