An alpha particle is the same as a Helium particle with a an atomic number of 2 and mass number of 4. For element 107 which is Bohrium (Bh), the balance equation is,
Bh - 266 --> Db - 264 + alpha particle
For element 109 (Meitnerium, Mt) given that the mass number of Bohrium is 266,
Mt - 270 --> Bh - 266 + alpha particle