Risa had $480 more than Lucy. Risa gave
23 of her money to Lucy. Lucy then gave 20% of her money to Risa. In the end, Lucy had $100 more than Risa. How much did Risa have at first?
| |
Risa |
Lucy |
Comparing Risa
and Lucy at first |
480 more |
|
| Before |
3 u |
+ 480 |
3 u |
|
| Change 1 |
- 2 u |
- 320 |
+ 2 u |
+ 320 |
| After 1 |
1 u |
+ 160 |
5 u |
+ 320 |
| Change 2 |
+ 1 u |
+ 64 |
- 1 u |
- 64 |
| After 2 |
2 u |
+ 224 |
4 u |
+ 256 |
23 x 480= 320
480 - 320 = 160
20% x 5 u
=
20100 x 5 u
= 1 u
20% x 320
=
20100 x 320
= 64
320 - 64 = 256
160 + 64 = 224
If Risa received another $100 in the end, Risa and Lucy would have the same amount of money.
4 u + 256 = 2 u + 224 + 100
4 u - 2 u = 224 + 100 - 256
2 u = 68
1 u = 68 ÷ 2 = 34
Amount that Risa had at first
= 3 u + 480
= 3 x 34 + 480
= 102 + 480
= $582
Answer(s): $582
