Seven years ago, the average age of A, B and C was 51 years. If A is 3 years older than B and B is 3 years older then C then the present ages of A, B and C are ( in year)
To travel 648 km, an Express train takes 12 hours more than Rajdhani. If however, the speed of the Express train is doubled, it takes 6 hours less than Rajdhani. The speed of Rajdhani is _____.