Shiyun and Tammy collected erasers. Tammy gave 80% of her erasers to Shiyun. As a result, Shiyun's erasers increased by 40%. If Shiyun had 84 erasers left, find the total number of erasers the two girls had at first.
| |
Comparing the change
in Tammy's erasers |
Tammy |
Shiyun |
| Before |
5x1 =
5 u |
|
5x2 =
10 u |
| Change |
- 4x1 =
- 4 u |
- 2x2 =
- 4 u |
+ 2x2 =
+ 4 u |
| After |
1x1 =
1 u |
|
7x2 =
14 u |
80% =
80100 =
45 40% =
40100 =
25 The number of erasers that Shiyun gave to Tammy is repeated. Make the number of erasers that Shiyun gave to Tammy the same. LCM of 2 and 4 is 4.
Number of erasers that Shiyun had in the end = 14 u
14 u = 84
1 u = 84 ÷ 14 = 6
Number of erasers that Tammy and Shiyun had at first
= 5 u + 10 u
= 15 u
= 15 x 6
= 90
Answer(s): 90
