Charlie's auntie is 4 times as old as him. His auntie will be 42 years old in 10 years' time. In how many years' time will Charlie's age be 60% that of his auntie's?
| |
Charlie's auntie |
Charlie |
Difference |
Before
(now) |
4x2 =
8 u |
1x2 =
2 u |
3x2 =
6 u |
| Change 1 |
+ 10 |
+ 10 |
|
| After 1 |
42 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
5x3 =
15 u |
3x3 =
9 u |
2x3 =
6 u |
60% =
60100 =
35 Charlie's auntie : Charlie = 5 : 3
The difference in age between Charlie's auntie and Charlie always remains the same. Make the difference in age between Charlie's auntie and Charlie the same. LCM of 3 and 2 is 6.
8 u + 10 = 42
8 u = 42 - 10
8 u = 32
1 u = 32 ÷ 8 = 4
Number of years' time when Charlie's age will be 60% that of his auntie's
= 15 u - 42
= 15 x 4 - 42
= 60 - 42
= 18
Answer(s): 18
