SOLUTION: Hi a train 128 meters long travelled through a tunnel at an average speed of 18m per sec. The whole train took 2min 36sec to pass through the tunnel. A car entered the same tunne

1.  First find the length of the tunnel, x (in meters).


    The train covers the length of the tunnel plus its own length in 2 min 36 seconds = 120 + 36 = 156 seconds.

    Hence, for the speed you have this equation   = 156, which gives

        x = 156*18-128 = 2680 meters.


    The length of the tunnel is 2680 meters.



2.  Both the train and the car reached their destination at the same time:

        train's time = car's time
       
           =  + 60         (60 = 1 minute = 60 seconds;   r is the car' speed in meters per second)
                                                   

    It is your equation to find the car' speed.

    Left side of the equation is   = 260.  Hence, you have, step by step

        260 =  + 60,

        260 - 60 = ,

        200 =   ====>  r =  = 23.4 m/s


Answer.  The length of the tunnel is 2680 meters.  The speed of the car is 23.4 m/s = 84.24 km/hour.