Seth's age is
15 of his grandfather's. His grandfather will be 43 years old in 3 years' time. In how many years' time will Seth's age be
35 that of his grandfather's?
| |
Seth |
His grandfather |
Difference |
| Before |
1x1 =
1 u |
5x1 =
5 u |
4x1 =
4 u |
| Change 1 |
+ 3 |
+ 3 |
|
| After |
|
43 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
3x2 =
6 u |
5x2 =
10 u |
2x2 =
4 u |
The age difference between Seth and his grandfather remains unchanged.
LCM of 4 and 2 is 4.
5 u + 3 = 43
5 u = 43 - 3
5 u = 40
1 u = 40 ÷ 5 = 8
Number of years' time when Seth's age will be
35 that of his grandfather's age
= 6 u - 1 u
= 5 u
= 5 x 8
= 40
Answer(s): 40
