Prove that the below maths equation is true.

8 + 8 = 91

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

You throw me out when you want to use me and you take me in when you don't want to use me.

Who Am I?

By moving just one matchstick, you need to make the below statement true. Can you do it?

Once upon a time, there was a castle on a square island. The entire island was surrounded by a 14m wide trench. The Romans had wanted to invade the castle and had brought a few wooden planks along with them to facilitate themselves in crossing the moat. The planks were however found to be only 13m long.

The Romans still managed to cross the trench. How did they do it?

By using 'because' continuously three times, can you make an English statement ?

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.

What does this rebus means ?

PROG WORKRESS

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

What is full of holes but still holds water?