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