The answer is 175 miles apart
First let get 3 inches. 1 inch equals 50 miles, 2 inches equals 100 miles, and 3 inches equals 150 miles. Now lets get the 1/2 inch. 50 miles is 1 inch so 25 miles is 1/2 inches. Add the 25 miles to the 150 and you get 175miles
Hope this helped☺