Oscar is 3 times as old as his brother. In 13 years' time, Oscar will be 9 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 |
+ 13 |
+ 13 |
|
After |
2 p - 9 |
1 p |
1 p - 9 |
Difference in their ages at first
= 3 u - 1 u
= 2 u
Difference in their ages in the end
= 2 p - 9 - 1 p
= 1 p - 9
The difference in their ages remains unchanged.
2 u = 1 p - 9
2 u + 9 =
1 p --- (1)
Age of Oscar's brother in 13 years' time
= 1 u + 13
1 u + 13 =
1 p --- (2)
(1) = (2)
2 u + 9 = 1 u + 13
2 u - 1 u = 13 - 9
1 u = 4
Oscar's current age
= 3 u
= 3 x 4
= 12
Oscar's age in 8 years' time
= 12 + 8
= 20
Answer(s): 20