Toby skated from his house to the beach at a constant speed of 8 kilometers per hour, and then skated from the beach to the park at a constant speed of 7 kilometers per hour. The total distance Toby skated was 20 kilometers, and it took him twice as long to get to the park. Let b be the number of hours it took Toby to skate from his house to the beach, and p the number of hours it took him to skate from the beach to the park. Find the values of b and p.