Elijah's father is 6 times as old as him. His father will be 28 years old in 4 years' time. In how many years' time will Elijah's age be 75% that of his father's?
| |
Elijah's father |
Elijah |
Difference |
Before
(now) |
6x1 =
6 u |
1x1 =
1 u |
5x1 =
5 u |
| Change 1 |
+ 4 |
+ 4 |
|
| After 1 |
28 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
4x5 =
20 u |
3x5 =
15 u |
1x5 =
5 u |
75% =
75100 =
34 Elijah's father : Elijah = 4 : 3
The difference in age between Elijah's father and Elijah always remains the same. Make the difference in age between Elijah's father and Elijah the same. LCM of 5 and 1 is 5.
6 u + 4 = 28
6 u = 28 - 4
6 u = 24
1 u = 24 ÷ 6 = 4
Number of years' time when Elijah's age will be 75% that of his father's
= 20 u - 28
= 20 x 4 - 28
= 80 - 28
= 52
Answer(s): 52
