Mark's current age is 3 times as old as Charlie's age years ago. Today, Charlie's age is Mark's age the same number of years ago. How old is Mark's age now if the total of their current age is 45?
| |
Mark |
Charlie |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
3 u |
1 p |
3 u - 1 p |
45 |
Total age of Mark and Charlie today = 3 u + 1 p
3 u + 1 p = 45 --- (1)
The difference in Mark's age and Charlie'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 = 45
3 u + 2 u = 45
5 u = 45
1 u = 45 ÷ 5 = 9
Mark's age now
= 3 u
= 3 x 9
= 27
Answer(s): 27
