A person reaches his destination 32 minutes late if his speed is 6 km/h, and reaches 18 minutes before time if his speed is 7 km/h. Find twice the distance (in km) of his destination from his starting point.
Person A can do one-fifth of the work in 3 days, while B's efficiency is half of that of A. In how many days A and B working together can do half of the work?