7 days ago, Tina had a total of 200 blue and brown stamps. 20% of her stamps were brown stamps. Today, her auntie gave her some more stamps. As a result, her blue stamps increased by 10%. Now, 50% of her stamps are brown stamps. How many brown stamps did her auntie give her?
| |
Brown stamps |
Blue stamps |
Total
stamps |
| Before |
1 u |
4 u |
200 |
| Change |
+ 3.4 u |
+ 0.4 u |
|
| After |
4.4 u |
4.4 u |
|
Comparing the
blue stamps and
brown stamps in the end |
1 |
1 |
|
20% =
20100 =
15 Brown stamps : Blue stamps = 1 : 4
Increase in the number of blue stamps
= 10% x 4 u
=
10100 x 4 u
= 0.4 u
50% =
50100 =
12 In the end
Brown stamps : Blue stamps = 1 : 1
Number of stamps at first
= 4 u + 1 u
= 5 u
5 u = 200
1 u = 200 ÷ 5 = 40
Number of brown stamps that Tina received from her auntie
= 4.4 u - 1 u
= 3.4 u
= 3.4 x 40
= 136
Answer(s): 136
