3 days ago, Min had a total of 200 purple and brown pens. 40% of her pens were brown pens. Today, her older sister gave her some more pens. As a result, her purple pens increased by 25%. Now, 50% of her pens are brown pens. How many brown pens did her older sister give her?
| |
Brown pens |
Purple pens |
Total
pens |
| Before |
2 u |
3 u |
200 |
| Change |
+ 1.75 u |
+ 0.75 u |
|
| After |
3.75 u |
3.75 u |
|
Comparing the
purple pens and
brown pens in the end |
1 |
1 |
|
40% =
40100 =
25 Brown pens : Purple pens = 2 : 3
Increase in the number of purple pens
= 25% x 3 u
=
25100 x 3 u
= 0.75 u
50% =
50100 =
12 In the end
Brown pens : Purple pens = 1 : 1
Number of pens at first
= 3 u + 2 u
= 5 u
5 u = 200
1 u = 200 ÷ 5 = 40
Number of brown pens that Min received from her older sister
= 3.75 u - 2 u
= 1.75 u
= 1.75 x 40
= 70
Answer(s): 70
