Sun City is a distance 230 km from Moon City when traveling along a straight highway that continues to extend beyond both cities. Suppose that Kharim passes Sun City at 4:00pm (while driving in the direction o Moon City) and remains at a constant speed of 80 km/hr. Bai passes Moon City at 4:15pm (driving in the direction of Sun City) and stays at a constant speed of 60 km/hr. Fill in the blank . At 6:00pm, how quickly is the distance between Kharim and Bai changing? km/hr. (Enter a number with NO space between the symbols) . If we let x denote that distance between Kharim and Bai at time t (in hours), does there exist some constant k for which @ = / for all t > 0? (Enter Y for "Yes" or N for "No")