The Hawaiian alphabet consists of $\displaystyle 12 $ letters, the vowels $\displaystyle \text{a}, \ \text{e}, \ \text{i}, \ \text{o}, \ \text{u} $ and the consonants $\displaystyle \text{h}, \ \text{k}, \ \text{l}, \ \text{m}, \ \text{n}, \ \text{p} $ and $\displaystyle \text{w} $.

(a) How many different four-letter words can be constructed using the $\displaystyle 12 $-letter alphabet?

(b) How about with the English alphabet?

(c) What is the second and last letters are vowels and the other $\displaystyle 2 $ are consonants?

(d) What if the second and last letters are vowels, but there are no restrictions on the other $\displaystyle 2 $ letters?

So for (a) it would be $\displaystyle 12^4 $. For (b) it would be $\displaystyle 26^4 $. For (c) it would be $\displaystyle 5^27^2 $. And for (d) it would be $\displaystyle 5^212^2 $?