Jack's current age is 3 times as old as George's age years ago. Today, George'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 30?
| |
Jack |
George |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
3 u |
1 p |
3 u - 1 p |
30 |
Total age of Jack and George today = 3 u + 1 p
3 u + 1 p = 30 --- (1)
The difference in Jack's age and George'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 = 30
3 u + 2 u = 30
5 u = 30
1 u = 30 ÷ 5 = 6
Jack's age now
= 3 u
= 3 x 6
= 18
Answer(s): 18
