Lucy and Xuan collected erasers. Xuan gave 70% of her erasers to Lucy. As a result, Lucy's erasers increased by 20%. If Lucy had 294 erasers left, find the total number of erasers the two girls had at first.
| |
Comparing the change
in Xuan's erasers |
Xuan |
Lucy |
| Before |
10x1 =
10 u |
|
5x7 =
35 u |
| Change |
- 7x1 =
- 7 u |
- 1x7 =
- 7 u |
+ 1x7 =
+ 7 u |
| After |
3x1 =
3 u |
|
6x7 =
42 u |
70% =
70100 =
710 20% =
20100 =
15 The number of erasers that Lucy gave to Xuan is repeated. Make the number of erasers that Lucy gave to Xuan the same. LCM of 1 and 7 is 7.
Number of erasers that Lucy had in the end = 42 u
42 u = 294
1 u = 294 ÷ 42 = 7
Number of erasers that Xuan and Lucy had at first
= 10 u + 35 u
= 45 u
= 45 x 7
= 315
Answer(s): 315
