What does this rebus riddle means ?

My grandson is about as many days as my son in weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 120 years. Can you tell me my age in years ?

What have one eye but still cannot see?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

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.'

All of you like to eat me. I am a five-lettered word. Remove the first two and I turn into an infamous animal. Remove just the first and I become a heinous crime. Remove the first and the last and you can groove on me.

Can you guess who am I?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

81 x 9 = 801. What must you do to make the this equation true?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?