Use the lists of factors to answer the question. Factors of 9: 1, 3, 9 Factors of 15: 1, 3, 5, 15 Factors of 21: 1, 3, 7, 21 Factors of 40: 1, 2, 4, 5, 8, 10, 20, 40 Which pairs of numbers are relatively prime? Check all that apply. 9 and 15 9 and 40 9 and 21 15 and 21 21 and 40

9 and 40

21 and 40

Step-by-step explanation:

Factors of 9:

1,3,9

Factors of 15:

1,3,5,15

Factors of 21:

1,3,7,21

Factors of 40:

1,2,4,5,8,10,20,40

We have to find the pairs of numbers which are relatively prime.

Relatively prime number: The numbers in which gcd 1 are called relative prime numbers.

a. 9 and 15

GCD (9,15) = 3

9 and 15 are not relatively prime.

b. 9 and 40

GCD (9,40) = 1

Hence, 9 and 40 are relatively prime.

c. 9 and 21

GCD (9,21) = 3

9 and 21 are not relatively prime.

d. 15 and 21

GCD (15,21) = 3

15 and 21 are not relatively prime.

e. 21 and 40

GCD (21,40) = 1

21 and 40 are relatively prime.