Sam's age is
25 of his grandfather's. His grandfather will be 69 years old in 19 years' time. In how many years' time will Sam's age be
710 that of his grandfather's?
| |
Sam |
His grandfather |
Difference |
| Before |
2x1 =
2 u |
5x1 =
5 u |
3x1 =
3 u |
| Change 1 |
+ 19 |
+ 19 |
|
| After |
|
69 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
7x1 =
7 u |
10x1 =
10 u |
3x1 =
3 u |
The age difference between Sam and his grandfather remains unchanged.
LCM of 3 and 3 is 3.
5 u + 19 = 69
5 u = 69 - 19
5 u = 50
1 u = 50 ÷ 5 = 10
Number of years' time when Sam's age will be
710 that of his grandfather's age
= 7 u - 2 u
= 5 u
= 5 x 10
= 50
Answer(s): 50
