Sean's age is
25 of his grandfather's. His grandfather will be 61 years old in 11 years' time. In how many years' time will Sean's age be
23 that of his grandfather's?
| |
Sean |
His grandfather |
Difference |
| Before |
2x1 =
2 u |
5x1 =
5 u |
3x1 =
3 u |
| Change 1 |
+ 11 |
+ 11 |
|
| After |
|
61 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
2x3 =
6 u |
3x3 =
9 u |
1x3 =
3 u |
The age difference between Sean and his grandfather remains unchanged.
LCM of 3 and 1 is 3.
5 u + 11 = 61
5 u = 61 - 11
5 u = 50
1 u = 50 ÷ 5 = 10
Number of years' time when Sean's age will be
23 that of his grandfather's age
= 6 u - 2 u
= 4 u
= 4 x 10
= 40
Answer(s): 40
