What is the greatest common factor of 72^2y and 18xy?

72^2y = 5184y

18xy = 18xy

72^2y factors (only some of them not All of them): 1, 2, 3, 4, 6, 8, 9, 12, 16, 18, y

18xy factors: 1, 2, 3, 6, 9, 18, x, y

Your 18xy (Option D.)

Note: Just rewrite the factors of the problem until you find out what you're looking for in the particular problem

Good Luck!

Ithink the answer is discovery verbs because they are quite similar to the verb 'discovering'