Ian's current age is 3 times as old as Tommy's age years ago. Today, Tommy's age is Ian's age the same number of years ago. How old is Ian's age now if the total of their current age is 20?
| |
Ian |
Tommy |
Difference |
Total |
| Before |
1 p |
1 u |
1 p - 1 u |
|
| Change |
+ ? |
+ ? |
|
|
| After |
3 u |
1 p |
3 u - 1 p |
20 |
Total age of Ian and Tommy today = 3 u + 1 p
3 u + 1 p = 20 --- (1)
The difference in Ian's age and Tommy'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 = 20
3 u + 2 u = 20
5 u = 20
1 u = 20 ÷ 5 = 4
Ian's age now
= 3 u
= 3 x 4
= 12
Answer(s): 12
