A flywheel slows from $703$ rev$/$min to $377$ rev$/$min while rotating through $53$ revolutions.

$($a$)$

What is the angular acceleration $($in rad$/$s$2)$ of the flywheel? $($Assume the flywheel is rotating in the positive direction. Indicate the direction with the sign of your answer.$)$

rad$/$s$2$

$($b$)$

How much time elapses $($in s$)$ during the $53$ revolutions?

s