Question

What prime factor is common to 35, 84 and 21?​

Answer 1

Answer: 7

35/7=5
84/7=12
21/7=3

5, 12, and 3 don’t have any common factors so 7 is the prime factor.

Answer 2

7 is the prime factor that is common to all three numbers.

7x5 = 35

7x12 = 84

7x3 = 21

Let me know if this helps!