the scale on a map is 1/4 inch to 4 miles. Find the actual distance between two towns for which the distance is represented by 25 inches on the map

You have a ratio of:

1/4 : 4 multiply both sides by 4 and you have:

1 : 16 Then multiply both sides by 25 and you have:

25 inches =16 x 25 = 400 miles - the actual distance.