Three girls, Wendy, Joelle and Lucy had a total of 1980 erasers. Some exchanges were made. First, Wendy gave Joelle as many erasers as Joelle had. After that, Joelle gave
13 of whatever she had then to Lucy. Finally, Lucy gave
15 of whatever she had to Wendy. As a result, they each had the same number of erasers. How many erasers did Wendy have at first?
|
Wendy |
Joelle |
Lucy |
Total |
Before 1 |
? |
1 u |
|
1980 |
Change 1 |
- 1 u |
+ 1 u |
|
|
After 1 |
|
2 u |
|
|
Before 2 |
|
3 p |
|
1980 |
Change 2 |
|
- 1 p |
+ 1 p |
|
After 2 |
|
2 p |
|
|
Before 3 |
|
|
5 boxes |
1980 |
Change 3 |
+ 1 box |
|
- 1 box |
|
After 3 |
|
|
4 boxes |
|
After 3 |
1 group |
1 group |
1 group |
1980 |
3 groups = 1980
1 group = 1980 ÷ 3 = 660
1 group = 4 boxes 4 boxes = 660
1 box = 660 ÷ 4 = 165
2 p = 1 group
1 p = 660 ÷ 2 = 330
3 p = 3 x 330 = 990
3 p = 2 u
2 u = 990
1 u = 990 ÷ 2 = 495
Number of erasers that Wendy had at first
= 1 group - 1 box + 1 u
= 660 - 165 + 495
= 990
Answer(s): 990