With the Extended Euclidean algorithm, we finally have an efficient algorithm for finding the modular inverse. Figure out whether there are the inverses of the following $x$ modulo $m.$ If yes, please use EEA to calculate it$.$ If not, please explain why.

$($a$)x=7,m=17(5$ points$)$

$($b$)x=13,m=85(10$ points$)$

$($c$)x=4,m=12(5$ points$)$