Explain how to solve this math problem: Jason drives past 3 convenience stores on his way to work. The distance between the first store and the second store is 6 miles. The distance between the second store and third store is 2/3rds longer than the distance between the first two stores. The distance from his house to the first store and the last store to work is the same, 4 miles. How long in miles is Jason's commute to work?