$($a$)$ A light$-$rail commuter train accelerates at a rate of $1\mathrm{.}35$m$/$s$2.$ How long does it take to reach its top speed

of $80\mathrm{.}0$ km$/$h$,$ starting from rest? $($b$)$ The same train ordinarily decelerates at a rate of $1\mathrm{.}65$m$/$s$2.$ How long does it take to come to a stop from its top speed? $($c$)$ In emergencies the train can decelerate more rapidly, coming to rest from $80\mathrm{.}0$ km$/$h in $8\mathrm{.}30$ s$.$ What is its emergency deceleration in m$/$s$2?$