Paul's age is
27 of his grandmother's. His grandmother will be 73 years old in 10 years' time. In how many years' time will Paul's age be
12 that of his grandmother's?
|
Paul |
His grandmother |
Difference |
Before |
2x1 = 2 u |
7x1 = 7 u |
5x1 = 5 u |
Change 1 |
+ 10 |
+ 10 |
|
After |
|
73 |
|
Change 2 |
+ ? |
+ ? |
|
After 2 |
1x5 = 5 u |
2x5 = 10 u |
1x5 = 5 u |
The age difference between Paul and his grandmother remains unchanged.
LCM of 5 and 1 is 5.
7 u + 10 = 73
7 u = 73 - 10
7 u = 63
1 u = 63 ÷ 7 = 9
Number of years' time when Paul's age will be
12 that of his grandmother's age
= 5 u - 2 u
= 3 u
= 3 x 9
= 27
Answer(s): 27