Wendy's uncle is 3 times as old as her. Wendy will be 15 years old in 3 years' time. In how many years' time will Wendy's age be 70% that of her uncle's?
| |
Wendy's uncle |
Wendy |
Difference |
Before
(now) |
3x3 =
9 u |
1x3 =
3 u |
2x3 =
6 u |
| Change 1 |
+ 3 |
+ 3 |
|
| After 1 |
|
15 |
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
10x2 =
20 u |
7x2 =
14 u |
3x2 =
6 u |
70% =
70100 =
710 Wendy's uncle : Wendy = 10 : 7
The difference in age between Wendy's uncle and Wendy always remains the same. Make the difference in age between Wendy's uncle and Wendy the same. LCM of 2 and 3 is 6.
3 u + 3 = 15
3 u = 15 - 3
3 u = 12
1 u = 12 ÷ 3 = 4
Number of years' time when Wendy's age will be 70% that of her uncle's
= 20 u - 39
= 20 x 4 - 39
= 80 - 39
= 41
Answer(s): 41
