+2441 To figure out this problem, list the factors of both 20 and 150 and see which number appears twice in both lists. Ordering them from least to greatest makes it simpler:
| Number | Factors of Number |
| 20 | 1, 2, 4, 5, 10, 20 |
| 150 | 1, 2, 3, 5, 6, 10, 15, 25, 30, 50, 75, 150 |
I have bolded the numbers that appear twice in the list. Those are the common factors. However, the question asks for the greatest one. Which one is greatest? 10! 10 is the greatest. That's your answer!
The GCF (greatest common factor) of 20 and 150 is 10!
