Jeremy's age is
17 of his grandfather's. His grandfather will be 65 years old in 9 years' time. In how many years' time will Jeremy's age be
12 that of his grandfather's?
| |
Jeremy |
His grandfather |
Difference |
| Before |
1x1 =
1 u |
7x1 =
7 u |
6x1 =
6 u |
| Change 1 |
+ 9 |
+ 9 |
|
| After |
|
65 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x6 =
6 u |
2x6 =
12 u |
1x6 =
6 u |
The age difference between Jeremy and his grandfather remains unchanged.
LCM of 6 and 1 is 6.
7 u + 9 = 65
7 u = 65 - 9
7 u = 56
1 u = 56 ÷ 7 = 8
Number of years' time when Jeremy's age will be
12 that of his grandfather's age
= 6 u - 1 u
= 5 u
= 5 x 8
= 40
Answer(s): 40
