Jack's current age is 9 times as old as Jeremy's age years ago. Today, Jeremy'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 28?
| |
Jack |
Jeremy |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
9 u |
1 p |
9 u - 1 p |
28 |
Total age of Jack and Jeremy today = 9 u + 1 p
9 u + 1 p = 28 --- (1)
The difference in Jack's age and Jeremy's age remains the same.
9 u - 1 p = 1 p - 1 u
9 u + 1 u = 1 p + 1 p
10 u = 2 p
5 u = 1 p
Substitute 1 p = 5 u into (1).
9 u + 1 p = 28
9 u + 5 u = 28
14 u = 28
1 u = 28 ÷ 14 = 2
Jack's age now
= 9 u
= 9 x 2
= 18
Answer(s): 18
