Risa and Rachel collected stamps. Risa gave 10% of her stamps to Rachel. As a result, Rachel's stamps increased by 80%. If Risa had 216 stamps left, find the total number of stamps the two girls had at first.
| |
Risa |
Rachel |
Comparing the change
in Rachel's stamps |
| 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 stamps that Risa gave to Rachel is repeated. Make the number of stamps that Risa gave to Rachel the same. LCM of 1 and 4 is 4.
Number of stamps that Risa had in the end = 36 u
36 u = 216
1 u = 216 ÷ 36 = 6
Number of stamps that Risa and Rachel had at first
= 40 u + 5 u
= 45 u
= 45 x 6
= 270
Answer(s): 270
