Question

In 2017, A is 9 years older than B who is five times as old as C. The total of the ages of A, B and C is 97 years. What would be the average of A and C ages in the year 2024 ?

Answer 1

A-B=9
B=C*5

A+B+C=97

A=49, B=40, C=8 in 2017
A=56, C=15 in 2024
Average of A and C in 2024 is (56+15)/2=35.5 years

Answer 2

In 2017:-
Let the Age of C=X
Then ,
Age of B=5X ( he is 5 times as old as C)
Age of A=5X+9 ( he is 9 years older than B)
By given conditions,
(5X+9)+5X+X=97
5X+5X+X+9=97
11X+9=97
11X=97-9=88
X=88/11=8
Therefore
A's age=5*8+9=49
B's age=5*8=40
C's age=8

In 2024:-( that is after 7 years)
A's age=49+7=56
B's age=40+7=47
C's age=8+7=15
Therefore average of A and C ages in 2024 =(56+15)/2=35.5