Billy's age is
37 of his granduncle's. His granduncle will be 76 years old in 20 years' time. In how many years' time will Billy's age be
35 that of his granduncle's?
| |
Billy |
His granduncle |
Difference |
| Before |
3x1 =
3 u |
7x1 =
7 u |
4x1 =
4 u |
| Change 1 |
+ 20 |
+ 20 |
|
| After |
|
76 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
3x2 =
6 u |
5x2 =
10 u |
2x2 =
4 u |
The age difference between Billy and his granduncle remains unchanged.
LCM of 4 and 2 is 4.
7 u + 20 = 76
7 u = 76 - 20
7 u = 56
1 u = 56 ÷ 7 = 8
Number of years' time when Billy's age will be
35 that of his granduncle's age
= 6 u - 3 u
= 3 u
= 3 x 8
= 24
Answer(s): 24
