They don't have the same denominators so you have to find a multiple. 12 is a multiple of both 3 and 4. In order to get a denominator of 12 for 2/3 you would have to multiply 3 by 4 and 2 by 4 leaving you with 8/12. Then you would have to multiply 1 by 3 and 4 by 3 leaving you with 3/12. Then you add them giving you 11/12. Hope this helps
