4. A sports car is being driven along a straight test track. It passes the point \(O\) at time \(t = 0\) at which time it begins to decelerate uniformly. The car passes the points \(L\) and \(M\) at times \(t = 1\) and \(t = 4\) respectively. Given that \(O L\) is 54 m and \(L M\) is 90 m ,

1. find the rate of deceleration of the car. The car subsequently comes to rest at \(N\).
2. Find the distance \(M N\).
   (4 marks)