Three girls, Mary, Abi and Wendy had a total of 3000 coins. Some exchanges were made. First, Mary gave Abi as many coins as Abi had. After that, Abi gave
13 of whatever she had then to Wendy. Finally, Wendy gave
13 of whatever she had to Mary. As a result, they each had the same number of coins. How many coins did Mary have at first?
|
Mary |
Abi |
Wendy |
Total |
Before 1 |
? |
1 u |
|
3000 |
Change 1 |
- 1 u |
+ 1 u |
|
|
After 1 |
|
2 u |
|
|
Before 2 |
|
3 p |
|
3000 |
Change 2 |
|
- 1 p |
+ 1 p |
|
After 2 |
|
2 p |
|
|
Before 3 |
|
|
3 boxes |
3000 |
Change 3 |
+ 1 box |
|
- 1 box |
|
After 3 |
|
|
2 boxes |
|
After 3 |
1 group |
1 group |
1 group |
3000 |
3 groups = 3000
1 group = 3000 ÷ 3 = 1000
1 group = 2 boxes 2 boxes = 1000
1 box = 1000 ÷ 2 = 500
2 p = 1 group
1 p = 1000 ÷ 2 = 500
3 p = 3 x 500 = 1500
3 p = 2 u
2 u = 1500
1 u = 1500 ÷ 2 = 750
Number of coins that Mary had at first
= 1 group - 1 box + 1 u
= 1000 - 500 + 750
= 1250
Answer(s): 1250