Elia rode her bicycle from her house to the beach at a constant speed of 18 kilometers per hour, and then rode from the beach to the park at a constant speed of 15 kilometers per hour. the total duration of the rides was 1 hour and the distance she rode in each direction are equal. let b be the number of hours it took elia to ride from her house to the beach, and put p the number of hours it took her to ride from the beach to the park.