Yen was 6 years old last year. She was 24 years younger than Kathy.
- How old will her Kathy be 7 years later?
- In how many years' time will Yen's age be 13 of Kathy's age?
| |
Yen |
Kathy |
Difference |
| Before (Last year) |
6 |
30 |
24 |
| Change 1 |
+ 1 |
+ 1 |
|
| After 1 (Now) |
7 |
31 |
24 |
| Change 2 |
+ 7 |
+ 7 |
|
| After 2 (7 years later) |
|
? |
24 |
(a)
Kathy's age this year
= 6 + 24
= 30
Kathy's age this year
= 30 + 1
= 31
Kathy's age in 7 years' time
= 31 + 7
= 38
| |
Yen |
Kathy |
Difference |
| Before |
7 |
31 |
24 |
| Change |
+ ? |
+ ? |
|
| After |
1 u |
3 u |
2 u |
(b)
The difference in the age between Yen and Kathy at first and in the end remains unchanged.
Difference in the age between Yen and Kathy
= 3 u - 1 u
= 2 u
2 u = 24
1 u = 24 ÷ 2 = 12
Number of years' time that Yen's age be
13 of Kathy's age
= 12 - 7
= 5
Answer(s): (a) 38; (b) 5
