Five years ago the average of A and B was 15 years. Average age of A,B and C today is 20 years how old will C be after 10 years?

A. 10 years
B. 20 years
C. 30 years
D. 40 years

According to the question,

=>P+Q/2=20

=>P+q=40

and P+Q+R/3=20

=>P+Q+R=60

On solving Eqs. (i) and (ii), we get

R = 20 yr

Therefore, Age of R after 10 yr from now

= 20 + 10

= 30 yr