Oscar's age is
25 of his granduncle's. His granduncle will be 70 years old in 15 years' time. In how many years' time will Oscar's age be
12 that of his granduncle's?
| |
Oscar |
His granduncle |
Difference |
| Before |
2x1 =
2 u |
5x1 =
5 u |
3x1 =
3 u |
| Change 1 |
+ 15 |
+ 15 |
|
| After |
|
70 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x3 =
3 u |
2x3 =
6 u |
1x3 =
3 u |
The age difference between Oscar and his granduncle remains unchanged.
LCM of 3 and 1 is 3.
5 u + 15 = 70
5 u = 70 - 15
5 u = 55
1 u = 55 ÷ 5 = 11
Number of years' time when Oscar's age will be
12 that of his granduncle's age
= 3 u - 2 u
= 1 u
= 1 x 11
= 11
Answer(s): 11
