Glen's mother is 4 times as old as him. His mother will be 30 years old in 6 years' time. In how many years' time will Glen's age be 75% that of his mother's?
| |
Glen's mother |
Glen |
Difference |
Before
(now) |
4x1 =
4 u |
1x1 =
1 u |
3x1 =
3 u |
| Change 1 |
+ 6 |
+ 6 |
|
| After 1 |
30 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
4x3 =
12 u |
3x3 =
9 u |
1x3 =
3 u |
75% =
75100 =
34 Glen's mother : Glen = 4 : 3
The difference in age between Glen's mother and Glen always remains the same. Make the difference in age between Glen's mother and Glen the same. LCM of 3 and 1 is 3.
4 u + 6 = 30
4 u = 30 - 6
4 u = 24
1 u = 24 ÷ 4 = 6
Number of years' time when Glen's age will be 75% that of his mother's
= 12 u - 30
= 12 x 6 - 30
= 72 - 30
= 42
Answer(s): 42
