Mrs Lim is 41 years old and her son is 7 years old now. In how many years' time will Mrs Lim be thrice as old as her son?
| |
Mrs Lim |
Her son |
Difference |
| Before |
41 |
7 |
34 |
| Change |
+ ? |
+ ? |
|
| After |
3 u |
1 u |
2 u |
The difference in the age between Mrs Lim and her son remains unchanged.
Difference in their age at first
= 41 - 7
= 34
Difference in their age in the end
= 3 u - 1 u
= 2 u
2 u = 34
1 u = 34 ÷ 2 = 17
Number of years time that Mrs Lim will be thrice as old as her son
= 1 u - 7
= 17 - 7
= 10
Answer(s): 10
