What was the question for this implicit rationale, and corresponding answer?
In five years, Phoebe will be 10 + 5 = 15 years old. If Raven is four times as old as Phoebe in fifteen years, he will be 4 * 15 = 60 years old in 5 years. Currently, Raven is 60 - 5 = 55 years old.
 The answer: 55
The question: In 5 years, Raven will be 4 times as old as Phoebe. If Phoebe is currently 10 years old, how old is Raven?