The ratio of Billy's age to Paul's age is 9 : 7. Last year, their average age was 15. How old will Paul be in 2 years' time?
|
Billy |
Paul |
Total |
Before |
9 u - 1 |
7 u - 1 |
30 |
Change |
+ 1 |
+ 1 |
|
After |
9 u |
7 u |
32 |
Total age of Billy and Paul this year
= 9 u + 7 u
= 16 u
Total age of Billy and Paul this year
= 2 x 15 + 1 + 1
= 30 + 2
= 32
16 u = 32
1 u = 32 ÷ 16 = 2
Paul's age in 2 years' time
= 7 u + 2
= 7 x 2 + 2
= 14 + 2
= 16
Answer(s): 16