A car is moving along a straight road. It passes a point A. After t second its distance, s m, from A is given by s = 10t - tsquared

a) find the time when the car passes through A again?

Don't know

b) find ds/dt? = 10 - 2t

c) find the maximum distance of the car from A.

We need to find ds/dt = 0

10 - 2t = 0

10 = 2t

t = 5 seconds

d) find the speed of the car 3 seconds after the passing of A.

10 - 6 = 4m/s

e) find the acceleration of the car

f''(x) which is -2

Please could someone help with question a) and check the rest? Many thanks in advance.