Opal's uncle is 4 times as old as her. Opal will be 16 years old in 8 years' time. In how many years' time will Opal's age be 60% that of her uncle's?
| |
Opal's uncle |
Opal |
Difference |
Before
(now) |
4x2 =
8 u |
1x2 =
2 u |
3x2 =
6 u |
| Change 1 |
+ 8 |
+ 8 |
|
| After 1 |
|
16 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
5x3 =
15 u |
3x3 =
9 u |
2x3 =
6 u |
60% =
60100 =
35 Opal's uncle : Opal = 5 : 3
The difference in age between Opal's uncle and Opal always remains the same. Make the difference in age between Opal's uncle and Opal the same. LCM of 3 and 2 is 6.
2 u + 8 = 16
2 u = 16 - 8
2 u = 8
1 u = 8 ÷ 2 = 4
Number of years' time when Opal's age will be 60% that of her uncle's
= 15 u - 40
= 15 x 4 - 40
= 60 - 40
= 20
Answer(s): 20
