Hello, Dried Monkey!

My grandson is about as many days as my son is weeks,

and my grandson is as many months as I am in years.

My grandson, my son, and I total 140 years.

Can you tell me my age in years?

Let: .

Let's take each sentence separately.

"My grandson is about as many days as my son is weeks."

My son's age in days is seven times my grandson's age in days.

That is, my son is seven times older than my grandson: .

"And my grandson is as many months as I am in years."

My grandson is years old; that is, he is months old.

Hence, we have: .

"My grandson, my son, and I total 140 years": .

We have a system of equations: .

And we have: .

Substitute into [1]: .

Substitute into [2]: .

Therefore, my grandson is 7, my son is 49, and I am 84.