Marion's uncle is 3 times as old as her. Marion will be 16 years old in 7 years' time. In how many years' time will Marion's age be 70% that of her uncle's?
| |
Marion's uncle |
Marion |
Difference |
Before
(now) |
3x3 =
9 u |
1x3 =
3 u |
2x3 =
6 u |
| Change 1 |
+ 7 |
+ 7 |
|
| After 1 |
|
16 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
10x2 =
20 u |
7x2 =
14 u |
3x2 =
6 u |
70% =
70100 =
710 Marion's uncle : Marion = 10 : 7
The difference in age between Marion's uncle and Marion always remains the same. Make the difference in age between Marion's uncle and Marion the same. LCM of 2 and 3 is 6.
3 u + 7 = 16
3 u = 16 - 7
3 u = 9
1 u = 9 ÷ 3 = 3
Number of years' time when Marion's age will be 70% that of her uncle's
= 20 u - 34
= 20 x 3 - 34
= 60 - 34
= 26
Answer(s): 26
