13 days ago, Lynn had a total of 200 yellow and pink stamps. 30% of her stamps were pink stamps. Today, her younger sister gave her some more stamps. As a result, her yellow stamps increased by 40%. Now, 50% of her stamps are pink stamps. How many pink stamps did her younger sister give her?
| |
Pink stamps |
Yellow stamps |
Total
stamps |
| Before |
3 u |
7 u |
200 |
| Change |
+ 6.8 u |
+ 2.8 u |
|
| After |
9.8 u |
9.8 u |
|
Comparing the
yellow stamps and
pink stamps in the end |
1 |
1 |
|
30% =
30100 =
310 Pink stamps : Yellow stamps = 3 : 7
Increase in the number of yellow stamps
= 40% x 7 u
=
40100 x 7 u
= 2.8 u
50% =
50100 =
12 In the end
Pink stamps : Yellow stamps = 1 : 1
Number of stamps at first
= 7 u + 3 u
= 10 u
10 u = 200
1 u = 200 ÷ 10 = 20
Number of pink stamps that Lynn received from her younger sister
= 9.8 u - 3 u
= 6.8 u
= 6.8 x 20
= 136
Answer(s): 136
