Which pair of numbers is relatively prime? a. 12 and 54 b. 9 and 21 c. 21 and 39 d. 15 and 49

D. 15 and 49

Step-by-step explanation:

Numbers are relatively prime if the only positive integer  that divides both of them is 1.

A. 12 and 54

both 12 and 54 can be divided by 3

12/3 =4   54/3 = 18

B. 9 and 21

both 9 and 21 can be divided by 3

9/3 =3  and 21/3 = 7

C. 21 and 39

both 21 and 39 can be divided by 3

21/3 =7 and 39/3 = 13

D. 15 and 49

13 is 3*5    and 49 is 7*7

This is relatively prime

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step-by-step explanation: