Answer: 1 is your answer!
Step-by-step explanation:
GCF = 1
for the values 14, 15, 21
Solution by Factorization:
The factors of 14 are: 1, 2, 7, 14
The factors of 15 are: 1, 3, 5, 15
The factors of 21 are: 1, 3, 7, 21
Then the greatest common factor is 1.