3. (12 points) Give a regular expression for the following languages, over the alphabet {a,b,c}:

(a) Words ending with b.

(b) Words with an odd number of bs, then a c, then an even number of as (e.g. bbbcaa and bcaaaa).

(c) Words where all the bs come before all the as, or all the cs come before all the bs. (e.g. cbcbacc, cccbbbcacac, aacaacbaaa, and cccbbbaaa)

(d) Words with an odd number of as. (e.g. bcbca and abcabcabbb).