Oscar is 3 times as old as his brother. In 15 years' time, Oscar will be 8 years less than twice of his brother's age. How old will Oscar be in 8 years' time?
| |
Oscar |
Oscar's brother |
Difference |
| Before |
3 u |
1 u |
2 u |
| Change |
+ 15 |
+ 15 |
|
| After |
2 p - 8 |
1 p |
1 p - 8 |
Difference in their ages at first
= 3 u - 1 u
= 2 u
Difference in their ages in the end
= 2 p - 8 - 1 p
= 1 p - 8
The difference in their ages remains unchanged.
2 u = 1 p - 8
2 u + 8 =
1 p --- (1)
Age of Oscar's brother in 15 years' time
= 1 u + 15
1 u + 15 =
1 p --- (2)
(1) = (2)
2 u + 8 = 1 u + 15
2 u - 1 u = 15 - 8
1 u = 7
Oscar's current age
= 3 u
= 3 x 7
= 21
Oscar's age in 8 years' time
= 21 + 8
= 29
Answer(s): 29
