Mark's age is
27 of his grandfather's. His grandfather will be 62 years old in 6 years' time. In how many years' time will Mark's age be
12 that of his grandfather's?
| |
Mark |
His grandfather |
Difference |
| Before |
2x1 =
2 u |
7x1 =
7 u |
5x1 =
5 u |
| Change 1 |
+ 6 |
+ 6 |
|
| After |
|
62 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x5 =
5 u |
2x5 =
10 u |
1x5 =
5 u |
The age difference between Mark and his grandfather remains unchanged.
LCM of 5 and 1 is 5.
7 u + 6 = 62
7 u = 62 - 6
7 u = 56
1 u = 56 ÷ 7 = 8
Number of years' time when Mark's age will be
12 that of his grandfather's age
= 5 u - 2 u
= 3 u
= 3 x 8
= 24
Answer(s): 24
