Billy's current age is 3 times as old as Warren's age years ago. Today, Warren's age is Billy's age the same number of years ago. How old is Billy's age now if the total of their current age is 40?
| |
Billy |
Warren |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
3 u |
1 p |
3 u - 1 p |
40 |
Total age of Billy and Warren today = 3 u + 1 p
3 u + 1 p = 40 --- (1)
The difference in Billy's age and Warren'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 = 40
3 u + 2 u = 40
5 u = 40
1 u = 40 ÷ 5 = 8
Billy's age now
= 3 u
= 3 x 8
= 24
Answer(s): 24
