Answer:
6 ft
Explanation:
You need to find the greatest common factor between 18 and 30. These numbers can be expressed as follows (using multiplication of prime numbers) .
18 = 2*3*3
30 = 2*3*5
2*3 = 6 appears in both cases and is the greatest common factor; therefore, 6 feet is the greatest distance apart that Al can place the fence post