Just to explain why the answer is 2/3. You need to find a factor that is in both of these numbers. So factors for 18 would be 2, 3, 6 and 9. Factors for 27 would be 3 and 9. 3 and 9 are in both, so these are what you should focus on. To get the simplest version, you should divide each side by the biggest number in your factor pairs, because that will get you the smallest answer. So 18/9=2 and 27/9=3. This gives 2 and 3 which is 2/3. Hope this helps :)