When Mr Pierre is 23 years old, his niece is 5 years old. In how many years will he be 3 times as old as his niece?
|
Mr Pierre |
His niece |
Difference |
Before |
23 |
5 |
18 |
Change |
+ ? |
+ ? |
|
After |
3 u |
1 u |
2 u |
The difference in the age between Mr Pierre and his niece at first and in the end remains the same.
Difference in the age between Mr Pierre and his niece
= 3 u - 1 u
= 2 u
2 u = 23 - 5
2 u = 18
1 u = 18 ÷ 2 = 9
Number of years' time so Mr Pierre will be 3 times as old as his niece
= 9 - 5
= 4
Answer(s): 4