8/18 plus 1/6 = 11/18
5/13 + 6/11 = = 133/143
11/6 + 1/3 = 11/2
13/9 or 11/3
11/30
17/11 or 1 6/11
6/16 + 11/18 = 284/288 which reduces to 71/72
11/12 + 11/12 = 22/12 = 1 and 5/6
1/3 + 5/6 = 7/6 or 11/6
5/6 + 1/12 = 11/12
16/20 + 6/20 = 11/10
The sum of 1/6 and 4/9 is 11/18.