Jack's current age is 3 times as old as Seth's age years ago. Today, Seth's age is Jack's age the same number of years ago. How old is Jack's age now if the total of their current age is 25?
|
Jack |
Seth |
Difference |
Total |
Before |
1 p |
1 u |
1 p - 1 u |
|
Change |
+ ? |
+ ? |
|
|
After |
3 u |
1 p |
3 u - 1 p |
25 |
Total age of Jack and Seth today = 3 u + 1 p
3 u + 1 p = 25 --- (1)
The difference in Jack's age and Seth'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 = 25
3 u + 2 u = 25
5 u = 25
1 u = 25 ÷ 5 = 5
Jack's age now
= 3 u
= 3 x 5
= 15
Answer(s): 15