The ratio of Sam's age to his son John's age is 8:3. If the sum of their ages is 55 years, what is the age difference between John and his dad in years?
So, I divided 55 by 11 and got 5, then multiplied that by 8 to get Sam's age (40), then the obvious remaining 15 years belong to John.
According to the answer key, the answer is 25. Can someone please explain how it is 25?