To solve each of these addition problems, we need to find a common denominator for each pair of fractions and then add them together.

4/9 + 3/5
Common denominator: 9 x 5 = 45
(4/9) (5/5) + (3/5) (9/9) = 20/45 + 27/45 = 47/45

11/25 + 13/30
Common denominator: 25 x 30 = 750
(11/25) (30/30) + (13/30) (25/25) = 330/750 + 325/750 = 655/750

7/18 + 7/12
Common denominator: 18 x 12 = 216
(7/18) (12/12) + (7/12) (18/18) = 84/216 + 126/216 = 210/216 = 35/36

5/42 + 1/7
Common denominator: 42
(5/42) + (6/42) = 11/42