All you do is find the cells in the table that match the criteria, and then add them together to get the probability.
(a) 1/20 (b) 11/24 (c) 1/2 (d) 7/30.
For (a) there is only one cell matching the values for X and Y: (1,2).
For (b) we have to add 3 cells: 1/12+1/4+1/8=11/24 (that is, (0,0)+(0,1)+(0,2)).
For (c) add (0,0), (0,1) and (1,0): 1/12+1/6+1/4=6/12=1/2.
For (d) add (1,0), (2,0) and (2,1): 1/6+1/24+1/40=(20+5+3)/120=28/120=7/30.