Problem $4.(10$ pts $=25)$ Answer the following questions.

a$)6\mathrm{.}23\mathrm{.}4=6$ times $4$ equals $24.$

b$)2=2$ times $3$ equals $6.$

c$)=$ for all a $$

$-$ False, considering a $=2\mathrm{.}8.$ For $,$ it will be $2.$ For $,$ it will be $3.$

d$)=1$ for all a $.$ True or False? Give a counterexample if false.

e$)$ Is $80$ congruent to $5$ modulo $17?$ Why, or why not?