The ratio of Tim's age to Riordan's age is 3 : 1. Last year, their average age was 17. How old will Riordan be in 9 years' time?
|
Tim |
Riordan |
Total |
Before |
3 u - 1 |
1 u - 1 |
34 |
Change |
+ 1 |
+ 1 |
|
After |
3 u |
1 u |
36 |
Total age of Tim and Riordan this year
= 3 u + 1 u
= 4 u
Total age of Tim and Riordan this year
= 2 x 17 + 1 + 1
= 34 + 2
= 36
4 u = 36
1 u = 36 ÷ 4 = 9
Riordan's age in 9 years' time
= 1 u + 9
= 1 x 9 + 9
= 9 + 9
= 18
Answer(s): 18