Give regular expressions generating the following languages over the alphabet $=\{a,b\}$ :

a$)$ begins with $b$ and ends with $a$

b$)$ contains at least $3$ a$\text{'}$s

c$)\{$ w $|$ w contains the substring abba$\}$

d$)\{$ w $|$ w has the length at least $3$ and its third symbol is a$\}$

e$)\{$ w $|$ w starts with a and has odd length, or starts with b and has even length$\}$

f$)\{$ w $|$ the length of w is at most $5\}$

g$)\{$ w $|$ w is any string except bab and bb$\}$

h$)\{$ w $|$ w is any string that has second last symbol equal to a$\}$