19) G

When a ß-paricle is emitted, an electron is emitted. This means that the proton number (atomic number) increases by 1. The mass number DOES NOT change when a ß-particle is emitted.
Therefore, X = W+1

When an α-particle is emitted, a Helium atom is emitted. This means that the mass number decreases by 4 and the atomic number decreases by 2.
So, Y = V-4

So the answer is G.