Formal Languages and Automa.I need help with problems b and c. Explain how it works and the process of doing these problems.

4. For ? {a, b), construct dfa's that accept the sets consisting of (a) all strings with exactly one a. (b) all strings with at least two a's. (c) all strings with no more than two a's. (d) all strings with at least one b and exactly two a's. (e) all the strings with exactly two a's and more than three b's