John's age is
17 of his granduncle's. His granduncle will be 69 years old in 13 years' time. In how many years' time will John's age be
12 that of his granduncle's?
| |
John |
His granduncle |
Difference |
| Before |
1x1 =
1 u |
7x1 =
7 u |
6x1 =
6 u |
| Change 1 |
+ 13 |
+ 13 |
|
| After |
|
69 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x6 =
6 u |
2x6 =
12 u |
1x6 =
6 u |
The age difference between John and his granduncle remains unchanged.
LCM of 6 and 1 is 6.
7 u + 13 = 69
7 u = 69 - 13
7 u = 56
1 u = 56 ÷ 7 = 8
Number of years' time when John's age will be
12 that of his granduncle's age
= 6 u - 1 u
= 5 u
= 5 x 8
= 40
Answer(s): 40
