The distance between pine bluff and river city is approx. 535.1 miles ( i had to search this up because without that information you cant find out your scale). 535.1 miles is 2 825 328 feet (or 535.1 X 5 280, because there are 5280 feet in a mile), and 2 825 328 feet is 33 903 936 inches (or 2 825 328 X 12, because there are 12 inches in a foot). Now if you take 33 903 936, and divide it by 6, which was how many inches were shown on your map, you get 5 650 656. and so, the scale on your map is 1:5 650 656, or for every 1 inch on your map, there are 5 650 656 inches in real life.