The ratio of Billy's age to Owen's age is 3 : 1. Last year, their average age was 15. How old will Owen be in 7 years' time?
|
Billy |
Owen |
Total |
Before |
3 u - 1 |
1 u - 1 |
30 |
Change |
+ 1 |
+ 1 |
|
After |
3 u |
1 u |
32 |
Total age of Billy and Owen this year
= 3 u + 1 u
= 4 u
Total age of Billy and Owen this year
= 2 x 15 + 1 + 1
= 30 + 2
= 32
4 u = 32
1 u = 32 ÷ 4 = 8
Owen's age in 7 years' time
= 1 u + 7
= 1 x 8 + 7
= 8 + 7
= 15
Answer(s): 15