Two people are on a city block. Person A is on the northeastcorner and Person B is on the southwest corner. Person A startswalking towards the southeast corner at a rate of 3 ft/sec. Fourseconds later Person B starts walking towards the southeast cornerat a rate of 2 ft/sec. At what rate is the distance between themchanging (a) 10 seconds after Person A startswalking and (b) after Person A has covered halfthe distance?
