Kylie was 5 years old last year. She was 28 years younger than Cathy.
- How old will her Cathy be 5 years later?
- In how many years' time will Kylie's age be 15 of Cathy's age?
| |
Kylie |
Cathy |
Difference |
| Before (Last year) |
5 |
33 |
28 |
| Change 1 |
+ 1 |
+ 1 |
|
| After 1 (Now) |
6 |
34 |
28 |
| Change 2 |
+ 5 |
+ 5 |
|
| After 2 (5 years later) |
|
? |
28 |
(a)
Cathy's age this year
= 5 + 28
= 33
Cathy's age this year
= 33 + 1
= 34
Cathy's age in 5 years' time
= 34 + 5
= 39
| |
Kylie |
Cathy |
Difference |
| Before |
6 |
34 |
28 |
| Change |
+ ? |
+ ? |
|
| After |
1 u |
5 u |
4 u |
(b)
The difference in the age between Kylie and Cathy at first and in the end remains unchanged.
Difference in the age between Kylie and Cathy
= 5 u - 1 u
= 4 u
4 u = 28
1 u = 28 ÷ 4 = 7
Number of years' time that Kylie's age be
15 of Cathy's age
= 7 - 6
= 1
Answer(s): (a) 39; (b) 1
