Liam's age is
37 of his grandmother's. His grandmother will be 70 years old in 7 years' time. In how many years' time will Liam's age be
12 that of his grandmother's?
|
Liam |
His grandmother |
Difference |
Before |
3x1 = 3 u |
7x1 = 7 u |
4x1 = 4 u |
Change 1 |
+ 7 |
+ 7 |
|
After |
|
70 |
|
Change 2 |
+ ? |
+ ? |
|
After 2 |
1x4 = 4 u |
2x4 = 8 u |
1x4 = 4 u |
The age difference between Liam and his grandmother remains unchanged.
LCM of 4 and 1 is 4.
7 u + 7 = 70
7 u = 70 - 7
7 u = 63
1 u = 63 ÷ 7 = 9
Number of years' time when Liam's age will be
12 that of his grandmother's age
= 4 u - 3 u
= 1 u
= 1 x 9
= 9
Answer(s): 9