4 miles represent one inch on the map.
This is because since they are 8 miles apart, and 2 inches in the map, and you want to find out how many miles per inch. You divide 8 by 2 because you want to divide how many miles by how many inches so that you can get 2 parts. That's how you get four.
Now that you cut 8 miles into two parts, you have halves, and half of eight is 4. And 1 inch represents that half since 1 + 1 equals 2 and 4 miles represents each of the two parts since 4+4 equals 8.
