Luis's age is
13 of his grandaunt's. His grandaunt will be 56 years old in 11 years' time. In how many years' time will Luis's age be
12 that of his grandaunt's?
| |
Luis |
His grandaunt |
Difference |
| Before |
1x1 =
1 u |
3x1 =
3 u |
2x1 =
2 u |
| Change 1 |
+ 11 |
+ 11 |
|
| After |
|
56 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x2 =
2 u |
2x2 =
4 u |
1x2 =
2 u |
The age difference between Luis and his grandaunt remains unchanged.
LCM of 2 and 1 is 2.
3 u + 11 = 56
3 u = 56 - 11
3 u = 45
1 u = 45 ÷ 3 = 15
Number of years' time when Luis's age will be
12 that of his grandaunt's age
= 2 u - 1 u
= 1 u
= 1 x 15
= 15
Answer(s): 15
