Answer:
2,3
Explanation:
Both 24 and 42 have two of the same prime factors which is 2 and 3. The prime factors of 24 are 2 and 3. Some of the prime factors of 42 is 2,3, and 7. 2 and 3 are prime numbers and 24 and 42 both have them as factors.
The Greatest Common Factor of 24 and 42 is 6.
Hope this helps.