Erika and Sarah collected buttons. Sarah gave 80% of her buttons to Erika. As a result, Erika's buttons increased by 10%. If Erika had 396 buttons left, find the total number of buttons the two girls had at first.
| |
Comparing the change
in Sarah's buttons |
Sarah |
Erika |
| Before |
5x1 =
5 u |
|
10x4 =
40 u |
| Change |
- 4x1 =
- 4 u |
- 1x4 =
- 4 u |
+ 1x4 =
+ 4 u |
| After |
1x1 =
1 u |
|
11x4 =
44 u |
80% =
80100 =
45 10% =
10100 =
110 The number of buttons that Erika gave to Sarah is repeated. Make the number of buttons that Erika gave to Sarah the same. LCM of 1 and 4 is 4.
Number of buttons that Erika had in the end = 44 u
44 u = 396
1 u = 396 ÷ 44 = 9
Number of buttons that Sarah and Erika had at first
= 5 u + 40 u
= 45 u
= 45 x 9
= 405
Answer(s): 405
