Three girls, Fiona, Risa and Diana had a total of 4920 stamps. Some exchanges were made. First, Fiona gave Risa as many stamps as Risa had. After that, Risa gave
13 of whatever she had then to Diana. Finally, Diana gave
13 of whatever she had to Fiona. As a result, they each had the same number of stamps. How many stamps did Fiona have at first?
|
Fiona |
Risa |
Diana |
Total |
Before 1 |
? |
1 u |
|
4920 |
Change 1 |
- 1 u |
+ 1 u |
|
|
After 1 |
|
2 u |
|
|
Before 2 |
|
3 p |
|
4920 |
Change 2 |
|
- 1 p |
+ 1 p |
|
After 2 |
|
2 p |
|
|
Before 3 |
|
|
3 boxes |
4920 |
Change 3 |
+ 1 box |
|
- 1 box |
|
After 3 |
|
|
2 boxes |
|
After 3 |
1 group |
1 group |
1 group |
4920 |
3 groups = 4920
1 group = 4920 ÷ 3 = 1640
1 group = 2 boxes 2 boxes = 1640
1 box = 1640 ÷ 2 = 820
2 p = 1 group
1 p = 1640 ÷ 2 = 820
3 p = 3 x 820 = 2460
3 p = 2 u
2 u = 2460
1 u = 2460 ÷ 2 = 1230
Number of stamps that Fiona had at first
= 1 group - 1 box + 1 u
= 1640 - 820 + 1230
= 2050
Answer(s): 2050