Oscar's current age is 3 times as old as Sean's age years ago. Today, Sean's age is Oscar's age the same number of years ago. How old is Oscar's age now if the total of their current age is 20?
| |
Oscar |
Sean |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
3 u |
1 p |
3 u - 1 p |
20 |
Total age of Oscar and Sean today = 3 u + 1 p
3 u + 1 p = 20 --- (1)
The difference in Oscar's age and Sean's age remains the same.
3 u - 1 p = 1 p - 1 u
3 u + 1 u = 1 p + 1 p
4 u = 2 p
2 u = 1 p
Substitute 1 p = 2 u into (1).
3 u + 1 p = 20
3 u + 2 u = 20
5 u = 20
1 u = 20 ÷ 5 = 4
Oscar's age now
= 3 u
= 3 x 4
= 12
Answer(s): 12
