What approximate values should come in place of the question mark(?) in the following question?

Prashant's monthly income is 30% more than that of Vimal. Vimal's monthly income is 20% less than that of Abhishek. If half of the value of the difference between the monthly income of Prashant and Abhishek is Rs.1800, what is the monthly income of Vimal? 

The average of nine consecutive odd numbers is 53. The least odd number is: 

The age of Shipra can be obtained by subtracting three times her age 3 years ago from the three times her age after 3 years. What will her age after 2 years?

Sita deposited Rs . 5,000 at 10 % simple interest for 2 years. How much more money will Sita have in her account at the end of two years. If it is compounded semiannually. 

Two trains starts from place A and B, 450 km apart towards each other. Both trains start simultaneously. A crow sitting on one train start flying at the same time towards the other train and as soon as it reaches the second train, it flies back to the first train and it continues in this manner flying backward and forwards from one train to the other until the train meet. Both train travel  at a speed of 45 km / h and the crow flies at 100 km / h total distance covered by the crow will be 

Train A crosses a stationary train B in 35 seconds and a pole in 14 seconds with the same speed. The length of the train A is 280 metres. What is the length of the stationary train B?