Shiyun and Barbara collected erasers. Shiyun gave 10% of her erasers to Barbara. As a result, Barbara's erasers increased by 70%. If Shiyun had 567 erasers left, find the total number of erasers the two girls had at first.
| |
Shiyun |
Barbara |
Comparing the change
in Barbara's erasers |
| Before |
10x7 =
70 u |
|
10x1 =
10 u |
| Change |
- 1x7 =
- 7 u |
+ 1x7 =
+ 7 u |
+ 7x1 =
+ 7 u |
| After |
9x7 =
63 u |
|
17x1 =
17 u |
10% =
10100 =
110 70% =
70100 =
710 The number of erasers that Shiyun gave to Barbara is repeated. Make the number of erasers that Shiyun gave to Barbara the same. LCM of 1 and 7 is 7.
Number of erasers that Shiyun had in the end = 63 u
63 u = 567
1 u = 567 ÷ 63 = 9
Number of erasers that Shiyun and Barbara had at first
= 70 u + 10 u
= 80 u
= 80 x 9
= 720
Answer(s): 720
