I'm currently working on some exercises to get used to create regular expressions from given languages and i'm stuck with a fairly simple exercise. So could you please tell me how to construct it step by step (if possible) from this given language. I would really appreciate your help.
L={w∈{a,b,c}∗:w contains an odd number of one or more of a,b or c}
For starters: an even number of $a$'s: $((b+c)^*a(b+c)^*a(b+c)^*)^*$.