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 ?

G = grandson's age
s = son's age
m = my age

"grandson is about as many days as my son is in weeks"
s = 7g

"my grandson is about as many weeks as i am in years"
m = 12g

"my grandon, my son and i together are 120 years old"
g + s + m = 120
g + (7g) + (12g) = 120
20g = 120
g = 6
s = 7g = 7(6) = 42
m = 12g = 12(6) = 72

My age in years is 72

So you're 120 in years so your grandson is 120 months, there's 12 months in a year .so times that by 10 - he's 10 years old. How many weeks are there in 10 years? 52 weeks in 1 year so times by 10 again and theres 520. So your grandson is 520 days old, 365 days in a year. 520 - 365 is 155. So he's 1 year and 155 days. The average month has 30.4 days per month (365.25/12) So 155 days would be 5.1 months or 5 months and 3 days.

So the final answer is 1 year, 5 months and 3 days.