Julian's father is 7 times as old as him. His father will be 51 years old in 9 years' time. In how many years' time will Julian's age be 60% that of his father's?
| |
Julian's father |
Julian |
Difference |
Before
(now) |
7x1 =
7 u |
1x1 =
1 u |
6x1 =
6 u |
| Change 1 |
+ 9 |
+ 9 |
|
| After 1 |
51 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
5x3 =
15 u |
3x3 =
9 u |
2x3 =
6 u |
60% =
60100 =
35 Julian's father : Julian = 5 : 3
The difference in age between Julian's father and Julian always remains the same. Make the difference in age between Julian's father and Julian the same. LCM of 6 and 2 is 6.
7 u + 9 = 51
7 u = 51 - 9
7 u = 42
1 u = 42 ÷ 7 = 6
Number of years' time when Julian's age will be 60% that of his father's
= 15 u - 51
= 15 x 6 - 51
= 90 - 51
= 39
Answer(s): 39
