Oscar is 5 times as old as his brother. In 14 years' time, Oscar will be 5 years less than twice of his brother's age. How old was Oscar 3 years ago?
| |
Oscar |
Oscar's brother |
Difference |
| Before |
5 u |
1 u |
4 u |
| Change |
+ 14 |
+ 14 |
|
| After |
2 p - 5 |
1 p |
1 p - 5 |
Difference in their ages at first
= 5 u - 1 u
= 4 u
Difference in their ages in the end
= 2 p - 5 - 1 p
= 1 p - 5
The difference in their ages remains unchanged.
4 u = 1 p - 5
4 u + 5 =
1 p --- (1)
Age of Oscar's brother in 14 years' time
= 1 u + 14
1 u + 14 =
1 p --- (2)
(1) = (2)
4 u + 5 = 1 u + 14
4 u - 1 u = 14 - 5
3 u = 9
1 u = 9 ÷ 3 = 3
Oscar's current age
= 5 u
= 5 x 3
= 15
Oscar's age 3 years ago
= 15 - 3
= 12
Answer(s): 12
