Answer
$2w$
Work Step by Step
Find the greatest common factor. Find the prime factors of each term and multiply the factors that are common to all the terms.
$8w^2=\underline2\times2\times2\times\underline w\times w$
$18w=3\times3\times\underline2\times\underline w$
GCF=$2\times w=2w$