Question

greatest common factor - item 6027
two numbers are between 10 and 20.
their greatest common factor is 3.
which two numbers could they be?
9 and 18
12 and 16
15 and 21
15 and 18

Explanation:

Step1: Check number range

Numbers must be between 10 and 20. Eliminate 9&18 (9<10), 15&21 (21>20).

Step2: Calculate GCF of 12&16

Factors of 12: 1,2,3,4,6,12; factors of 16:1,2,4,8,16. GCF=4≠3.

Step3: Calculate GCF of 15&18

Factors of15:1,3,5,15; factors of18:1,2,3,6,9,18. GCF=3. Matches condition.

Answer:

15 and 18