Erika was 7 years old last year. She was 28 years younger than Opal.
- How old will her Opal be 4 years later?
- In how many years' time will Erika's age be 13 of Opal's age?
| |
Erika |
Opal |
Difference |
| Before (Last year) |
7 |
35 |
28 |
| Change 1 |
+ 1 |
+ 1 |
|
| After 1 (Now) |
8 |
36 |
28 |
| Change 2 |
+ 4 |
+ 4 |
|
| After 2 (4 years later) |
|
? |
28 |
(a)
Opal's age this year
= 7 + 28
= 35
Opal's age this year
= 35 + 1
= 36
Opal's age in 4 years' time
= 36 + 4
= 40
| |
Erika |
Opal |
Difference |
| Before |
8 |
36 |
28 |
| Change |
+ ? |
+ ? |
|
| After |
1 u |
3 u |
2 u |
(b)
The difference in the age between Erika and Opal at first and in the end remains unchanged.
Difference in the age between Erika and Opal
= 3 u - 1 u
= 2 u
2 u = 28
1 u = 28 ÷ 2 = 14
Number of years' time that Erika's age be
13 of Opal's age
= 14 - 8
= 6
Answer(s): (a) 40; (b) 6
