Marion's father is 3 times as old as her. Marion will be 14 years old in 5 years' time. In how many years' time will Marion's age be 70% that of her father's?
| |
Marion's father |
Marion |
Difference |
Before
(now) |
3x3 =
9 u |
1x3 =
3 u |
2x3 =
6 u |
| Change 1 |
+ 5 |
+ 5 |
|
| After 1 |
|
14 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
10x2 =
20 u |
7x2 =
14 u |
3x2 =
6 u |
70% =
70100 =
710 Marion's father : Marion = 10 : 7
The difference in age between Marion's father and Marion always remains the same. Make the difference in age between Marion's father and Marion the same. LCM of 2 and 3 is 6.
3 u + 5 = 14
3 u = 14 - 5
3 u = 9
1 u = 9 ÷ 3 = 3
Number of years' time when Marion's age will be 70% that of her father's
= 20 u - 32
= 20 x 3 - 32
= 60 - 32
= 28
Answer(s): 28
