The brakes are applied to a moving vehicle, causing it to uniformly slow down. While slowing, it moves a distance of $40\mathrm{.}0$ m in $7\mathrm{.}80$ s to a final velocity of $1\mathrm{.}35$ m$/$s$,$ at which point the brakes are released. 

a$)$ What was its initial speed $($in m$/$s$),$ just before the brakes were applied?

How is average velocity related to displacement and time? How is average velocity related to initial and final velocity $($when acceleration is uniform$)?$ Use these relationships to solve for initial velocity. 

$($b$)$ What was its acceleration $($in m$/$s$\mathrm{²})$ while the brakes were applied? $($Assume the initial direction of motion is the positive direction. Indicate the direction with the sign of your answer.$)$