Cole's age is
37 of his grandmother's. His grandmother will be 87 years old in 3 years' time. In how many years' time will Cole's age be
12 that of his grandmother's?
| |
Cole |
His grandmother |
Difference |
| Before |
3x1 =
3 u |
7x1 =
7 u |
4x1 =
4 u |
| Change 1 |
+ 3 |
+ 3 |
|
| After |
|
87 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
1x4 =
4 u |
2x4 =
8 u |
1x4 =
4 u |
The age difference between Cole and his grandmother remains unchanged.
LCM of 4 and 1 is 4.
7 u + 3 = 87
7 u = 87 - 3
7 u = 84
1 u = 84 ÷ 7 = 12
Number of years' time when Cole's age will be
12 that of his grandmother's age
= 4 u - 3 u
= 1 u
= 1 x 12
= 12
Answer(s): 12
