A racing car moving with constant acceleration covers two successive kilometers in 30s and 20s respectively. Find the acceleration of the car.

Ans= 2/3 m/s2

PLEASE HELP! :O

Let u be the initial velocity and a be the acceleration.

1000 = u(30) + 0.5a(30)(30)= 30u + 450a

Velocity after covering 1 km is u + 30a

1000 = (u + 30a)(20) + 0.5a(20)(20)= 20u + 800a

Solving we get u = 35a

Therefore, a = (2/3)