(i)[2]
No restrictions apply.
(ii)[1]
The As are in the $1\text{st}$, $5\text{th}$ and $9\text{th}$ positions.
(iii)[4]
Exactly one letter lies between the Ms.
(iv)[1]
Find the number of different selections when the three letters contain exactly one M and exactly one A.
(v)[3]
Find the number of different selections when the three letters include at least one M.