Lucy will be 47 years old in 14 years' time. Now, Risa's age is 23 of Lucy's age. What was Risa's age when she was 5 years less than 80% of Lucy's age?
| |
Risa |
Lucy |
Difference |
| Before |
4 p - 5 |
5 p |
1 p + 5 |
| Change 1 |
+ ? |
+ ? |
|
| After 1 (Now) |
2 u |
3 u |
1 u |
| Change 2 |
+ 14 |
+ 14 |
|
| After |
2 u + 14 |
47 |
|
Lucy's age in 14 years' time = 3 u + 14
3 u + 14 = 47
3 u = 47 - 14
3 u = 33
1 u = 33 ÷ 3 = 11
Difference between Lucy's age and Risa's age
= 1 u
= 11
80% =
80100 =
45 Difference in Lucy's age and Risa's age at first
= 5 p - (4 p - 5)
= 1 p + 5
The difference in age between Lucy and Risa remains unchanged.
1 p + 5 = 11
1 p = 11 - 5 = 6
Risa's age when she was 5 years less than 80% of Lucy's age
= 4 p - 5
= 4 x 6 - 5
= 24 - 5
= 19
Answer(s): 19
