This is DFA, can you show me the steps? (create a machine)

Thank you

2. (25 points) Answer the 18110WIIg questions. (a) (10 points) Prove that D = { x {a}* | #a(x) is divisible by 3 } is regular. (b) (10 points) Prove that E = { x {a}* | #a(x) is divisible by 4 } is regular. (c) (20 points) Prove that F = { x E {a}* | #a(x) is divisible by 3 or 4 } is regular by constructing a product machine from D and E