Answer:(a) The smallest possible distance between the two towns would be 12km (the distance to Bergville) + 15km (the distance to Reddington) = 27km. The largest possible distance would be 12km + 15km + 1km (the margin of error for each distance being given to the nearest kilometer) = 28km.
(b) The possible difference in the distance the two walkers walk would be the difference in the distances given on the sign, which is 15km - 12km = 3km. However, this difference would also be affected by the margin of error of 1km for each distance given on the sign, so the possible difference in distance could range from 2km to 4km.