Mrs Yap is 45 years old and her daughter is 6 years old now. In how many years' time will Mrs Yap be four times as old as her daughter?
| |
Mrs Yap |
Her daughter |
Difference |
| Before |
45 |
6 |
39 |
| Change |
+ ? |
+ ? |
|
| After |
4 u |
1 u |
3 u |
The difference in the age between Mrs Yap and her daughter remains unchanged.
Difference in their age at first
= 45 - 6
= 39
Difference in their age in the end
= 4 u - 1 u
= 3 u
3 u = 39
1 u = 39 ÷ 3 = 13
Number of years time that Mrs Yap will be four times as old as her daughter
= 1 u - 6
= 13 - 6
= 7
Answer(s): 7
