Three girls, Hazel, Jean and Jaslyn had a total of 1680 pens. Some exchanges were made. First, Hazel gave Jean as many pens as Jean had. After that, Jean gave
15 of whatever she had then to Jaslyn. Finally, Jaslyn gave
15 of whatever she had to Hazel. As a result, they each had the same number of pens. How many pens did Hazel have at first?
|
Hazel |
Jean |
Jaslyn |
Total |
Before 1 |
? |
1 u |
|
1680 |
Change 1 |
- 1 u |
+ 1 u |
|
|
After 1 |
|
2 u |
|
|
Before 2 |
|
5 p |
|
1680 |
Change 2 |
|
- 1 p |
+ 1 p |
|
After 2 |
|
4 p |
|
|
Before 3 |
|
|
5 boxes |
1680 |
Change 3 |
+ 1 box |
|
- 1 box |
|
After 3 |
|
|
4 boxes |
|
After 3 |
1 group |
1 group |
1 group |
1680 |
3 groups = 1680
1 group = 1680 ÷ 3 = 560
1 group = 4 boxes 4 boxes = 560
1 box = 560 ÷ 4 = 140
4 p = 1 group
1 p = 560 ÷ 4 = 140
5 p = 5 x 140 = 700
5 p = 2 u
2 u = 700
1 u = 700 ÷ 2 = 350
Number of pens that Hazel had at first
= 1 group - 1 box + 1 u
= 560 - 140 + 350
= 770
Answer(s): 770