If each 1/2 inch on a map represents 20 miles, how many inches apart on the map are two cities whose actual distance apart is 120 miles?
I need to find a proportion that relates the map scale to the actual distance. I can write the proportion as 1/2 inch over 20 miles equals x inches over 120 miles. To solve for x, I can cross-multiply and get 20x = 1/2 * 120. Simplifying, I get 20x = 60. Dividing both sides by 20, I get x = 3. So the two cities are 3 inches apart on the map. 