10 days ago, Lucy had a total of 220 pink and blue stamps. 25% of her stamps were blue stamps. Today, her younger sister gave her some more stamps. As a result, her pink stamps increased by 40%. Now, 50% of her stamps are blue stamps. How many blue stamps did her younger sister give her?
| |
Blue stamps |
Pink stamps |
Total
stamps |
| Before |
1 u |
3 u |
220 |
| Change |
+ 3.2 u |
+ 1.2 u |
|
| After |
4.2 u |
4.2 u |
|
Comparing the
pink stamps and
blue stamps in the end |
1 |
1 |
|
25% =
25100 =
14 Blue stamps : Pink stamps = 1 : 3
Increase in the number of pink stamps
= 40% x 3 u
=
40100 x 3 u
= 1.2 u
50% =
50100 =
12 In the end
Blue stamps : Pink stamps = 1 : 1
Number of stamps at first
= 3 u + 1 u
= 4 u
4 u = 220
1 u = 220 ÷ 4 = 55
Number of blue stamps that Lucy received from her younger sister
= 4.2 u - 1 u
= 3.2 u
= 3.2 x 55
= 176
Answer(s): 176
