Explanation:
The scale is 1 inch : 4 miles
You can read this is 1 inch to 4 miles.
Since your question is slightly unclear, please bear with me.
If you need to find the distance between two places, measuring using a ruler the length between the two places. Make sure to use inches. For every inch measured, there is 4 miles of distance. Multiply the inches by 4 and replace the units with miles.
Ex: 3 inches => 12 miles
To find the distances for the measurements you gave:
3 inches
3 X 4 = 12
3 inches is 12 miles
7.5 inches
7.5 X 4 = 30
7.5 inches is 30 miles
1 foot. This uses a different unit. 1 foot is the same as 12 inches.
12 X 4 = 48.
1 foot is 48 miles
