Five years ago, the average age of P and Q was 25. The average age of P, Q and R today is 25. Age of R after 5 years will be :

Answer: Option B

According to the question,
$$\frac{P+Q}{2}$$ = 25
P + Q = 50.....(i) (5 years ago)
$$\frac{P+Q+R}{3}$$   = 25
P + Q + R = 75.....(ii) (present age)
∴ Present age of P + Q = 50 + 10 = 60 years
Present age of R = 75 - 60 = 15 years
∴ Age of R after 5 years
= 15 + 5 = 20 years