Rachel's mother is 4 times as old as her. Rachel will be 9 years old in 3 years' time. In how many years' time will Rachel's age be 60% that of her mother's?
| |
Rachel's mother |
Rachel |
Difference |
Before
(now) |
4x2 =
8 u |
1x2 =
2 u |
3x2 =
6 u |
| Change 1 |
+ 3 |
+ 3 |
|
| After 1 |
|
9 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
5x3 =
15 u |
3x3 =
9 u |
2x3 =
6 u |
60% =
60100 =
35 Rachel's mother : Rachel = 5 : 3
The difference in age between Rachel's mother and Rachel always remains the same. Make the difference in age between Rachel's mother and Rachel the same. LCM of 3 and 2 is 6.
2 u + 3 = 9
2 u = 9 - 3
2 u = 6
1 u = 6 ÷ 2 = 3
Number of years' time when Rachel's age will be 60% that of her mother's
= 15 u - 27
= 15 x 3 - 27
= 45 - 27
= 18
Answer(s): 18
