Answer:
The actual area 21600 miles²
Step-by-step explanation:
* <em>Lets explain how to solve the problem</em>
- A drawing that shows a real object with accurate sizes reduced or
  enlarged by a certain amount called the scale 
- Drawing scale is a ratio between the drawing length and the 
  actual length
- To find the actual dimensions from the drawing dimensions use the 
   scale drawing 
*<em> Lets solve the problem</em>
- A map of a rectangular park has a length of 4 inches and a width
  of 6 inches
∴ The drawing dimensions are:
# length = 4 inches
# width = 6 inches
- The scale of the map is 1 inch foe every 30 miles
∴ The scale drawing is 1 : 30
- To find the actual area find the actual dimensions
∵ The scale drawing is 1 : 30
∵ The length = 4 inches and the width = 6 inches
- By using cross multiplication
∴  1        :        30
    4       :  actual length 
    6       :  actual width
∴ Actual length = (4 × 30)/1 = 120 
∴ Actual length = 120 miles
∴ Actual width = (6 × 30)/1 = 180 
∴ Actual Width = 180 miles
∴ The actual dimensions are 120 miles and 180 miles
∵ The area of any rectangle = length × width
∴ The actual area = 120 × 180 = 21600 
∴ The actual area 21600 miles²