Anna and Yoko collected erasers. Anna gave 25% of her erasers to Yoko. As a result, Yoko's erasers increased by 70%. If Anna had 231 erasers left, find the total number of erasers the two girls had at first.
|
Anna |
Yoko |
Comparing the change in Yoko's erasers |
Before |
4x7 = 28 u |
|
10x1 = 10 u |
Change |
- 1x7 = - 7 u |
+ 1x7 = + 7 u |
+ 7x1 = + 7 u |
After |
3x7 = 21 u |
|
17x1 = 17 u |
25% =
25100 =
14 70% =
70100 =
710 The number of erasers that Anna gave to Yoko is repeated. Make the number of erasers that Anna gave to Yoko the same. LCM of 1 and 7 is 7.
Number of erasers that Anna had in the end = 21 u
21 u = 231
1 u = 231 ÷ 21 = 11
Number of erasers that Anna and Yoko had at first
= 28 u + 10 u
= 38 u
= 38 x 11
= 418
Answer(s): 418