Two Families

When Dr. White and Dr. Green met each other 5 years ago, each family had only one child. Now they each have two children under 10 years old. These are the facts about their children:
1) James is the oldest among the four;
2) Russell is 4 years older than his brother;
3) Stephen's age is half of one of Dr. White's children's age;
4) Kevin is 2 years older than Dr. Green's younger child.
If each child is a different age, how old is Stephen?

Timed Exam

Leo plans to take a timed exam. He fills the corresponding bubble in the answer sheet right after completing each problem. If he spends 2 minutes to complete each problem, he would have 6 problems on the answer sheet left empty. If he spends 1 minute on each problem, he would have 4 minutes left before the end of the exam. Let N be the number of problems in the exam. What's the least value for N?

Memorial Day

Memorial Day, observed on the last Monday of May, is a U.S. federal holiday for honoring and mourning the military personnel who had died while serving in the United States Armed Forces. One year, there were four Saturdays and four Wednesdays in the month of May. On which day of May was Memorial Day?

Greatest Possible GCF

Sum of five different positive integers is 2020. What is the greatest possible greatest common factor of the five?