Three girls, Lynn, Kathy and Penelope had a total of 2640 erasers. Some exchanges were made. First, Lynn gave Kathy as many erasers as Kathy had. After that, Kathy gave
15 of whatever she had then to Penelope. Finally, Penelope gave
13 of whatever she had to Lynn. As a result, they each had the same number of erasers. How many erasers did Lynn have at first?
|
Lynn |
Kathy |
Penelope |
Total |
Before 1 |
? |
1 u |
|
2640 |
Change 1 |
- 1 u |
+ 1 u |
|
|
After 1 |
|
2 u |
|
|
Before 2 |
|
5 p |
|
2640 |
Change 2 |
|
- 1 p |
+ 1 p |
|
After 2 |
|
4 p |
|
|
Before 3 |
|
|
3 boxes |
2640 |
Change 3 |
+ 1 box |
|
- 1 box |
|
After 3 |
|
|
2 boxes |
|
After 3 |
1 group |
1 group |
1 group |
2640 |
3 groups = 2640
1 group = 2640 ÷ 3 = 880
1 group = 2 boxes 2 boxes = 880
1 box = 880 ÷ 2 = 440
4 p = 1 group
1 p = 880 ÷ 4 = 220
5 p = 5 x 220 = 1100
5 p = 2 u
2 u = 1100
1 u = 1100 ÷ 2 = 550
Number of erasers that Lynn had at first
= 1 group - 1 box + 1 u
= 880 - 440 + 550
= 990
Answer(s): 990