Rael's mother is 4 times as old as him. His mother will be 28 years old in 4 years' time. In how many years' time will Rael's age be 75% that of his mother's?
| |
Rael's mother |
Rael |
Difference |
Before
(now) |
4x1 =
4 u |
1x1 =
1 u |
3x1 =
3 u |
| Change 1 |
+ 4 |
+ 4 |
|
| After 1 |
28 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
4x3 =
12 u |
3x3 =
9 u |
1x3 =
3 u |
75% =
75100 =
34 Rael's mother : Rael = 4 : 3
The difference in age between Rael's mother and Rael always remains the same. Make the difference in age between Rael's mother and Rael the same. LCM of 3 and 1 is 3.
4 u + 4 = 28
4 u = 28 - 4
4 u = 24
1 u = 24 ÷ 4 = 6
Number of years' time when Rael's age will be 75% that of his mother's
= 12 u - 28
= 12 x 6 - 28
= 72 - 28
= 44
Answer(s): 44
