When Mr Lee is 20 years old, his nephew is 2 years old. In how many years will he be 3 times as old as his nephew?
| |
Mr Lee |
His nephew |
Difference |
| Before |
20 |
2 |
18 |
| Change |
+ ? |
+ ? |
|
| After |
3 u |
1 u |
2 u |
The difference in the age between Mr Lee and his nephew at first and in the end remains the same.
Difference in the age between Mr Lee and his nephew
= 3 u - 1 u
= 2 u
2 u = 20 - 2
2 u = 18
1 u = 18 ÷ 2 = 9
Number of years' time so Mr Lee will be 3 times as old as his nephew
= 9 - 2
= 7
Answer(s): 7
