Jerry was 1/3 as young as his grandfather 15 years ago. If the sum of their ages is 110, how old is Jerry's grandfather?
Let grandfather's age was x years 15 years ago. So Jerry's age was
Hence 15 years ago sum of their's age was 110 - 15*2 = 80 years.
So as per questions,
Therefore 15 years ago grandfather's age was 60 years.
Now grandfather's age is 60 + 15 = 75 years.