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