Ahmad's current age is 3 times as old as Rael's age years ago. Today, Rael's age is Ahmad's age the same number of years ago. How old is Rael's age now if the total of their current age is 20?
| |
Ahmad |
Rael |
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 Ahmad and Rael today = 3 u + 1 p
3 u + 1 p = 20 --- (1)
The difference in Ahmad's age and Rael'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
Ahmad's age now
= 20 - 3 u
= 20 - 3 x 4
= 20 - 12
= 8
Answer(s): 8
