Answer:
15 and 39 are not coprime
Step-by-step explanation:
Coprime numbers have only 1 as a common factor
factors of 15 are 1 , 3 , 5 , 15
factors of 39 are 1 , 3 , 13 , 39
15 and 39 have common factors of 1 and 3
Thus 15 and 39 are not coprime numbers