Final answer:
The greatest common factor of 20 and 25 is 5, which is the largest number that can evenly divide both numbers.
Step-by-step explanation:
The greatest common factor (GCF) of two numbers is the largest number that divides both of them without leaving a remainder. To find the GCF of 20 and 25, first list the factors of each number.
- Factors of 20: 1, 2, 4, 5, 10, 20
- Factors of 25: 1, 5, 25
Now, look for the largest factor that appears in both lists. In this case, the greatest common factor is 5.