Gem and Mary collected stamps. Gem gave 40% of her stamps to Mary. As a result, Mary's stamps increased by 80%. If Gem had 72 stamps left, find the total number of stamps the two girls had at first.
| |
Gem |
Mary |
Comparing the change
in Mary's stamps |
| Before |
5x2 =
10 u |
|
5x1 =
5 u |
| Change |
- 2x2 =
- 4 u |
+ 2x2 =
+ 4 u |
+ 4x1 =
+ 4 u |
| After |
3x2 =
6 u |
|
9x1 =
9 u |
40% =
40100 =
25 80% =
80100 =
45 The number of stamps that Gem gave to Mary is repeated. Make the number of stamps that Gem gave to Mary the same. LCM of 2 and 4 is 4.
Number of stamps that Gem had in the end = 6 u
6 u = 72
1 u = 72 ÷ 6 = 12
Number of stamps that Gem and Mary had at first
= 10 u + 5 u
= 15 u
= 15 x 12
= 180
Answer(s): 180
