Solution:

two hours.

Harish who could paint the wall in 3 hours could paint 2/3 of the wall in just two hours. Ganpat who paint the wall in 6 hours could paint 1/3 of the wall in two hours.
2/3 + 1/3 = 1.

Solution:

12,345,678,987,654,321

(its amazing and awesome)

Solution:

Both would be the same distance from City owlna. (since they are at a same point)

Solution:

199 - 99

Solution:

100/9 (fraction number is also a number)

lets say 'X' is the number.
10/X = X - 10
9X = 100
X = 100/9

Solution:

40 balls

Solution:

The train is just about to leave the station and there is no way tarun will be able to catch it this time.

Solution:

Lady:135 , Baby:25 & Dog:10

Solution:

Hockey Stick $49.50 & ball $0.50

Solution:

The required number is 236 and the sum is 11.

It is given that the first two digits of the required number are prime numbers i.e. 2, 3, 5 or 7. Note that 1 is neither prime nor composite. Also, the third digit is the multiplication of the first two digits. Thus, first two digits must be either 2 or 3 i.e.
22, 23, 32 or 33 which means that there are four possible numbers - 224, 236,326 and 339.
Now, it is also given that - the difference between it's reverse and itself is 396.
Only 236 satisfies this condition. Hence, the sum of the three digits is 11.