Mrs Lau is 41 years old and her cousin is 8 years old now. In how many years' time will Mrs Lau be four times as old as her cousin?
| |
Mrs Lau |
Her cousin |
Difference |
| Before |
41 |
8 |
33 |
| Change |
+ ? |
+ ? |
|
| After |
4 u |
1 u |
3 u |
The difference in the age between Mrs Lau and her cousin remains unchanged.
Difference in their age at first
= 41 - 8
= 33
Difference in their age in the end
= 4 u - 1 u
= 3 u
3 u = 33
1 u = 33 ÷ 3 = 11
Number of years time that Mrs Lau will be four times as old as her cousin
= 1 u - 8
= 11 - 8
= 3
Answer(s): 3
