$10-$ Perform the following conversions:

a$)$ The decimal $8549$ to BCD code and excess$-3$ code $(2$ points$).$

b$)$ The hexadecimal FABEEBAF.CDE to binary and octal $(4$ points$).$

c$)$ The octal $67543210\mathrm{.}04$ to binary and hexadecimal $(4$ points$).$