14 days ago, Diana had a total of 225 grey and brown stamps. 40% of her stamps were brown stamps. Today, her cousin gave her some more stamps. As a result, her grey stamps increased by 20%. Now, 50% of her stamps are brown stamps. How many brown stamps did her cousin give her?
| |
Brown stamps |
Grey stamps |
Total
stamps |
| Before |
2 u |
3 u |
225 |
| Change |
+ 1.6 u |
+ 0.6 u |
|
| After |
3.6 u |
3.6 u |
|
Comparing the
grey stamps and
brown stamps in the end |
1 |
1 |
|
40% =
40100 =
25 Brown stamps : Grey stamps = 2 : 3
Increase in the number of grey stamps
= 20% x 3 u
=
20100 x 3 u
= 0.6 u
50% =
50100 =
12 In the end
Brown stamps : Grey stamps = 1 : 1
Number of stamps at first
= 3 u + 2 u
= 5 u
5 u = 225
1 u = 225 ÷ 5 = 45
Number of brown stamps that Diana received from her cousin
= 3.6 u - 2 u
= 1.6 u
= 1.6 x 45
= 72
Answer(s): 72
