![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
If the greatest common factor of two or more numbers is 1, then they are
\relatively prime.
\Greatest common factor (GCF) is a number that is greatest among the
\common factors of the numbers.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step2.JPG\")
List the factors of each number.
\Factors of 21: 3, 7, 21
\Factors of 160: 2, 4, 5, 8, 10, 20, 40, 80, 160
\There are no common prime factors.
\Two numbers always have 1 as a common factor.
\So, the greatest common factor is 1.
\Since the GCF is 1, the numbers are relativety prime.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
There are no common prime factors.
\Two numbers always have 1 as a common factor. So, the GCF is 1.
\21 and 160 are relativety prime.