How many of the positive factors of 15 , 45 and how many common factors are there in numbers? Choose one
A) 1  B) 2  C) 3  D) 4  E) 5

Rationale: factors of 15 - 1 , 3 , 5 , and 15 factors of 45 - 1 , 3 , 9 , 15 and 45 comparing both , we have three common factors of 45,16 - 3 answer c
Answer: C