Sean's age is
25 of his grandaunt's. His grandaunt will be 69 years old in 4 years' time. In how many years' time will Sean's age be
12 that of his grandaunt's?
| |
Sean |
His grandaunt |
Difference |
| Before |
2x1 =
2 u |
5x1 =
5 u |
3x1 =
3 u |
| Change 1 |
+ 4 |
+ 4 |
|
| After |
|
69 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x3 =
3 u |
2x3 =
6 u |
1x3 =
3 u |
The age difference between Sean and his grandaunt remains unchanged.
LCM of 3 and 1 is 3.
5 u + 4 = 69
5 u = 69 - 4
5 u = 65
1 u = 65 ÷ 5 = 13
Number of years' time when Sean's age will be
12 that of his grandaunt's age
= 3 u - 2 u
= 1 u
= 1 x 13
= 13
Answer(s): 13
