1. Alpha
Number next to Th is 231
(because 231 + 4 = 235)
The other number below the 4 is 2 - helium
(because 90 + 2 = 92)
2. Beta
Missing numbers are zero and one. Same as the one below it.
3. Beta
11 is the number above the C
(because 11 + 0 = 11)
5 is the number next to the B
(because 5 + 1 = 6)
Basically, the missing numbers must balance on both side of the equation; creating the elements you've started of with, meaning if you where to add the right side of the equation up - you should end up with the same protons and mass numbers you began with.
Hope this helps!