Gillian and Anna collected erasers. Gillian gave 10% of her erasers to Anna. As a result, Anna's erasers increased by 80%. If Gillian had 72 erasers left, find the total number of erasers the two girls had at first.
| |
Gillian |
Anna |
Comparing the change
in Anna's erasers |
| Before |
10x4 =
40 u |
|
5x1 =
5 u |
| Change |
- 1x4 =
- 4 u |
+ 1x4 =
+ 4 u |
+ 4x1 =
+ 4 u |
| After |
9x4 =
36 u |
|
9x1 =
9 u |
10% =
10100 =
110 80% =
80100 =
45 The number of erasers that Gillian gave to Anna is repeated. Make the number of erasers that Gillian gave to Anna the same. LCM of 1 and 4 is 4.
Number of erasers that Gillian had in the end = 36 u
36 u = 72
1 u = 72 ÷ 36 = 2
Number of erasers that Gillian and Anna had at first
= 40 u + 5 u
= 45 u
= 45 x 2
= 90
Answer(s): 90
