Suggest a structure for each of the ions corresponding to the following peaks in the EI mass

Question:

Suggest a structure for each of the ions corresponding to the following peaks in the EI mass spectrum of ethyl bromide, and give a mechanism for the formation of each ion. (The numbers in parentheses are the relative abundances.)
(a) m/z= 108 (100%)
(b) m/z= 79 (5%)
(c) m/z= 28 (25%)