To add 5/9 and 3/4, we need a common denominator. The least common denominator between 9 and 4 is 36.

5/9 = 20/36
3/4 = 27/36

20/36 + 27/36 = (20 + 27) / 36 = 47/36

To subtract 23/40 and 3/8, we need a common denominator. The least common denominator between 40 and 8 is 40.

23/40 - 3/8 = 23/40 - 15/40 = (23 - 15) / 40 = 8/40 = 1/5

To subtract 9/35 and 3/28, we need a common denominator. The least common denominator between 35 and 28 is 140.

9/35 = 36/140
3/28 = 15/140

36/140 - 15/140 = (36 - 15) / 140 = 21/140 = 3/20

Therefore, the calculations are:

5/9 + 3/4 = 47/36
23/40 - 3/8 = 1/5
9/35 - 3/28 = 3/20