The more of this there is, the less you see. What is it?

O_er_t_o_

Complete the missing letters of the given word.

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

How many times can you subtract the number two from the number fifty?

I have a clock(12-hour format) and both the needles of the clock overlap at 12:00.
After how much time, they will overlap again?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

The Puzzle: A girl, a boy, and a dog start walking down a road.

They start at the same time, from the same point, in the same direction.

The boy walks at 5 km/h, the girl at 6 km/h.

The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?

1 rabbit saw 9 elephants while going to the river. Every elephant saw 3 monkeys going toward the river. Each monkey had 1 parrot in each hand. How many animals are going towards the river?