What common phrase is represented by the below lines

Easy going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Medium going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Tough going:
Weak, 'I can't do it, I'm staying!'
Tough, 'Let's get going.'

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Who is generally closer to the kids, mom or dad?

(it's a funny riddle)

What is next number in the pattern below:

131 517 192 123 ?

A man has eighty-one cows ( numbered 1,2,3...81 as such). The beauty is that cow no. 1 gives 1ltr of milk, cow no. 2 gives 2ltrs of milk and so on. The man wants to equally distribute the cows among his nine sons so that each one of them gets the same quantity of milk.

If 21x = 79x, what is the value of x?

A large container is kept in open under the rain. Every passing hour, the water collected inside the container becomes double what it was.

In ten hours, the container is filled completely. Can you calculate how long would it have taken to be filled in half?

What do you see in the given picture?

Look at the picture and find out which square is not linked with any of the other squares.

What is the next number in this matchsticks series riddle?