8/13 + 3/13, 18 + 4/19, 2 7/9 + 8/9, 4 1/2 + 3 1/4, 31/60 + 29/60, 23 + 9/10, 15 8/11 + 4 3/11, 5 1/7 + 3 20 21

8/13 + 3/13 = 11/13 18 + 4/19 = 18 4/19 2 7/9 + 8/9 = 3 8/9 4 1/2 + 3 1/4 = 7 3/4 31/60 +29/60 = 5/6 23 + 9/10 = 23 9/10 15 8/11 + 4 3/11 = 19 11/11 5 1/7 + 3 20 21 = 9 27/7