Three girls, Shannon, Jean and Gillian had a total of 4620 pens. Some exchanges were made. First, Shannon gave Jean as many pens as Jean had. After that, Jean gave
13 of whatever she had then to Gillian. Finally, Gillian gave
15 of whatever she had to Shannon. As a result, they each had the same number of pens. How many pens did Shannon have at first?
|
Shannon |
Jean |
Gillian |
Total |
Before 1 |
? |
1 u |
|
4620 |
Change 1 |
- 1 u |
+ 1 u |
|
|
After 1 |
|
2 u |
|
|
Before 2 |
|
3 p |
|
4620 |
Change 2 |
|
- 1 p |
+ 1 p |
|
After 2 |
|
2 p |
|
|
Before 3 |
|
|
5 boxes |
4620 |
Change 3 |
+ 1 box |
|
- 1 box |
|
After 3 |
|
|
4 boxes |
|
After 3 |
1 group |
1 group |
1 group |
4620 |
3 groups = 4620
1 group = 4620 ÷ 3 = 1540
1 group = 4 boxes 4 boxes = 1540
1 box = 1540 ÷ 4 = 385
2 p = 1 group
1 p = 1540 ÷ 2 = 770
3 p = 3 x 770 = 2310
3 p = 2 u
2 u = 2310
1 u = 2310 ÷ 2 = 1155
Number of pens that Shannon had at first
= 1 group - 1 box + 1 u
= 1540 - 385 + 1155
= 2310
Answer(s): 2310