Complete parts $($a$)$ through $($c$)$ below.

a$.$ Find two unit vectors parallel to $v=-24i+10j.$

b$.$ Find $b$ if $v=($:$\frac{1}{8},b)$ is a unit vector.

c$.$ Find all values of a such that $w=ai-\frac{a}{10}j$ is a unit vector.

a$.$ The parallel unit vector with the same direction is $$

The parallel unit vector with the opposite direction is $$

b$.b=$

$($Type exact answers. Use a comma to separate answers as needed.$)$

c$.a=$

$($Type exact answers. Use a comma to separate answers as needed.$)$