Oscar is 3 times as old as his brother. In 16 years' time, Oscar will be 13 years less than twice of his brother's age. How old will Oscar be in 4 years' time?
|
Oscar |
Oscar's brother |
Difference |
Before |
3 u |
1 u |
2 u |
Change |
+ 16 |
+ 16 |
|
After |
2 p - 13 |
1 p |
1 p - 13 |
Difference in their ages at first
= 3 u - 1 u
= 2 u
Difference in their ages in the end
= 2 p - 13 - 1 p
= 1 p - 13
The difference in their ages remains unchanged.
2 u = 1 p - 13
2 u + 13 =
1 p --- (1)
Age of Oscar's brother in 16 years' time
= 1 u + 16
1 u + 16 =
1 p --- (2)
(1) = (2)
2 u + 13 = 1 u + 16
2 u - 1 u = 16 - 13
1 u = 3
Oscar's current age
= 3 u
= 3 x 3
= 9
Oscar's age in 4 years' time
= 9 + 4
= 13
Answer(s): 13